TaskEval¶

TaskEval applies Karenina's evaluation engine (templates for correctness, rubrics for quality) to text you supply, without generating responses.

1. What Is TaskEval?¶

Karenina has two evaluation workflows. Benchmark is a closed-loop workflow: it defines questions, sends them to an answering model through the verification pipeline, and evaluates the generated responses. TaskEval is the open-loop counterpart. You supply pre-existing text (an agent trace, a pipeline output, a human-written response) and evaluate it using the same pipeline, the same templates, the same rubrics, and the same judge LLM. No question definition or answer generation is required.

The abstraction boundary: TaskEval handles recording text, attaching evaluation criteria, and routing evaluation through the verification pipeline. It does not generate responses, manage questions, or provide persistence. It is a stateless evaluation container: you populate it, evaluate, and read the results.

Use TaskEval whenever you have text that already exists and needs structured evaluation:

• Agent workflows that produce multi-step traces you want to score for correctness or quality
• CI pipelines that capture outputs from production runs and need post-hoc quality checks
• One-off experiments where you want to evaluate a response against a template or rubric without building a full benchmark

2. Why TaskEval Exists¶

Many evaluation scenarios start with text that already exists. A coding agent produced a solution. A RAG pipeline returned a synthesis. A production system logged a response. In all these cases, the text is already produced; what you need is a way to evaluate it.

Benchmark assumes it controls the full loop: it sends a question to a model, captures the response, and evaluates it. If your text was produced by a different system, at a different time, or through a process Benchmark cannot orchestrate (a multi-step agent, a human annotator, an external API), you need a way to feed that text directly into the evaluation engine.

The most important idea is that TaskEval reuses the same verification pipeline as Benchmark. Internally, it injects your text as cached_answer_data, bypassing the answer generation stage while running every subsequent stage identically: template validation, judge parsing, verify(), rubric evaluation, abstention detection, and metric computation. The evaluation quality is the same; only the source of the text being evaluated differs.

Benchmark mode:                  TaskEval mode:
  Questions + Answering Model      Pre-existing text
          │                              │
          ▼                              ▼
  Generate Answer (Stage 2)        cached_answer_data
          │                              │
          └───────────┬──────────────────┘
                      ▼
            Stages 3-13 (identical)
            Parse → Verify → Rubric
                      │
                      ▼
               VerificationResult

3. How It Works¶

TaskEval is a recording and evaluation container with a three-phase lifecycle.

3.1 Phase 1: Record¶

External code produces text. You record it into a TaskEval instance using log() for plain strings or log_trace() for structured conversation traces (lists of Message objects from karenina.ports.messages). Each call appends to the TaskEval's internal log store.

If your process has distinct phases, you can assign each log entry to a named step via the step_id parameter. An agent workflow with a retrieval phase and a synthesis phase can record outputs separately under step_id="retrieval" and step_id="synthesis". Logs without a step_id go to the global scope.

3.2 Phase 2: Attach Evaluation Criteria¶

Once text is recorded, you attach evaluation criteria: templates for correctness, rubrics for quality, or both.

A template is a structured Pydantic schema that tells the judge LLM what to extract from the text, paired with a verify() method that checks the extracted values against ground truth. A rubric defines qualitative dimensions (conciseness, citation quality, logical coherence) that the judge LLM scores independently from factual correctness.

Criteria can be attached globally (evaluated against all recorded text) or to a specific step (evaluated against only that step's logs). The evaluation mode is auto-detected from what you attach: template_only, rubric_only, or template_and_rubric.

3.3 Phase 3: Evaluate¶

Calling evaluate() sends the recorded text through Karenina's verification pipeline. The pipeline's judge LLM parses the text into any attached templates, runs verify(), and scores each rubric trait. TaskEval returns a TaskEvalResult containing verification outcomes for both global and per-step scopes.

3.4 Walkthrough¶

Suppose an agent workflow looked up a cancer drug and produced this output:

"The primary pharmacological target of venetoclax is BCL2 (B-cell lymphoma 2), a protein that inhibits apoptosis. Venetoclax binds selectively to BCL2, displacing pro-apoptotic proteins and triggering programmed cell death in cancer cells [1]."

You want to evaluate this along two dimensions:

1. Correctness: Did the response identify BCL2 as the primary target? This is a template check: a boolean field (identifies_bcl2) and a verify() method that compares it against ground truth.
2. Quality: Is the response concise and well cited? These are rubric traits, scored by the judge LLM.

You would record this text with log(), attach a template for the BCL2 check and a rubric for conciseness, then call evaluate(). The verification pipeline handles judge parsing, verify(), and trait scoring. The workflow page shows the complete code for this scenario.

4. Benchmark vs TaskEval¶

Dimension	Benchmark	TaskEval
Workflow	Closed-loop: generate + evaluate	Open-loop: evaluate only
Starting point	Questions (define what to ask)	Text (record what happened)
Answer generation	Pipeline generates responses	You supply pre-recorded text
Question definition	Required	Not required
Pipeline stages used	All 13 stages	Same pipeline; generation stage bypassed
Result type	VerificationResult (per question/model)	TaskEvalResult (global + per-step)
Best for	Controlled model comparison	Evaluating existing outputs

When to use which:

• Use Benchmark when you control the question-and-answer loop: you have questions, you want to send them to one or more models, and you want to compare the results.
• Use TaskEval when the text already exists: an agent produced a trace, a pipeline captured an output, or you are working with outputs from a system Benchmark cannot orchestrate.

A useful litmus test: if you need answering_models in your VerificationConfig, you need Benchmark. If you only need parsing_models (with parsing_only=True), TaskEval is the right tool.

5. Object Structure¶

A TaskEval instance holds two parallel scopes: global and per-step. Each scope stores logs (the text to evaluate), templates (correctness criteria), and rubrics (quality criteria).

In [2]:

from karenina.benchmark.task_eval import TaskEval

task = TaskEval(
    task_id="agent-drug-target",
    metadata={"model": "claude-haiku-4-5"},
)

from karenina.benchmark.task_eval import TaskEval task = TaskEval( task_id="agent-drug-target", metadata={"model": "claude-haiku-4-5"}, )

┌───────────────────────────────────────────────────────┐
│                      TaskEval                         │
│                                                       │
│  task_id: "agent-drug-target"                         │
│  metadata: {"model": "claude-haiku-4-5"}              │
│  merge_strategy: "concatenate"                        │
│                                                       │
│  ┌─────────────────────────────────────────────────┐  │
│  │ Global Scope                                    │  │
│  │                                                 │  │
│  │  logs        ← log(), log_trace()               │  │
│  │  templates   ← add_template(Answer)             │  │
│  │  rubrics     ← add_rubric(Rubric)               │  │
│  └─────────────────────────────────────────────────┘  │
│                                                       │
│  ┌──────────────────┐  ┌──────────────────┐           │
│  │ Step: retrieval  │  │ Step: synthesis  │  ...      │
│  │                  │  │                  │           │
│  │  logs            │  │  logs            │           │
│  │  templates       │  │  templates       │           │
│  │  rubrics         │  │  rubrics         │           │
│  └──────────────────┘  └──────────────────┘           │
└───────────────────────────────────────────────────────┘

The global scope evaluates all logs together. Per-step scopes evaluate only the logs, templates, and rubrics attached to that step. When you call evaluate() without a step_id, TaskEval runs global evaluation first, then automatically evaluates each step that has data.

The constructor accepts two additional parameters: merge_strategy (see Merge Strategies) and callable_registry, a dict[str, Callable] for pre-registering functions used by callable rubric traits.

6. Attaching Evaluation Criteria¶

Pass a BaseAnswer subclass via add_template() for correctness checks, and a Rubric via add_rubric() for quality traits. Both can be scoped globally or to a specific step via the step_id parameter.

The evaluation mode is auto-detected from what you attach:

You attach	Detected mode	Pipeline behavior
Template only	template_only	Judge parses response into template; verify() runs
Rubric only	rubric_only	A synthetic pass-through template is created internally; rubric traits are scored
Both	template_and_rubric	Full evaluation: template parsing, verify(), and rubric scoring

In [3]:

# Correctness: judge LLM parses the response into Answer, then verify() runs
task.add_template(Answer)

# Quality: each trait is scored independently by the judge LLM
task.add_rubric(Rubric(llm_traits=[
    LLMRubricTrait(name="conciseness", kind="boolean",
                   description="True if the response is direct and avoids unnecessary elaboration.")
]))

# Correctness: judge LLM parses the response into Answer, then verify() runs task.add_template(Answer) # Quality: each trait is scored independently by the judge LLM task.add_rubric(Rubric(llm_traits=[ LLMRubricTrait(name="conciseness", kind="boolean", description="True if the response is direct and avoids unnecessary elaboration.") ]))

add_template() requires inspectable source

add_template() extracts the source code of your BaseAnswer subclass using inspect.getsource(). The class must be defined in a .py file or Jupyter notebook, not constructed dynamically at runtime. For dynamically defined templates, use add_question() with template source code passed as a string in the answer_template field.

If your rubric includes callable traits, register the callable functions before calling evaluate():

In [ ]:

task.register_callable("under_150_words", lambda text: len(text.split()) < 150)

task.register_callable("under_150_words", lambda text: len(text.split()) < 150)

When multiple rubrics are attached to the same scope, TaskEval merges them into a single rubric. Trait names must be unique across all rubrics in the same scope; duplicate names raise a ValueError.

See the workflow for complete examples including all trait types and step-scoped criteria.

7. Logging¶

Use log() for plain text and log_trace() for structured Message traces from karenina.ports.messages. Both accept step_id to scope output to a named step and target to control where the log is stored.

In [4]:

# Plain text
task.log("BCL2 is the primary pharmacological target of venetoclax.")
task.log("Found 3 relevant papers.", step_id="retrieval")

# Structured trace
task.log_trace([
    Message.user("What is the target of venetoclax?"),
    Message.assistant("The primary pharmacological target of venetoclax is BCL2."),
])

# Plain text task.log("BCL2 is the primary pharmacological target of venetoclax.") task.log("Found 3 relevant papers.", step_id="retrieval") # Structured trace task.log_trace([ Message.user("What is the target of venetoclax?"), Message.assistant("The primary pharmacological target of venetoclax is BCL2."), ])

The target parameter controls routing when a step_id is provided:

target value	Global scope	Step scope	Use when
"both" (default)	Yes	Yes (requires step_id)	The log is relevant to both overall and step-specific evaluation
"global"	Yes	No	The step_id is for bookkeeping, but the text should only appear in global evaluation
"step"	No	Yes (requires step_id)	The text is relevant only to this step, not the overall evaluation

Without a step_id, only the global scope receives the log regardless of the target value.

log_trace() also accepts a plain string, which is automatically wrapped as a single Message.assistant() object. When structured traces contain tool calls, the full message structure (including tool use and tool results) is preserved for the pipeline.

See the workflow for complete parameter reference and tool call trace examples.

8. Merge Strategies¶

When evaluation runs, TaskEval combines logged outputs into a single response for the verification pipeline. The merge_strategy parameter controls this merging:

Strategy	Behavior	Use when
"concatenate" (default)	Text logs are wrapped as Message.assistant() objects; trace messages are included as-is. All messages are serialized together into a single response string.	You want all logged output evaluated together
"traces_only"	Only logs that contain structured Message traces are used. Text-only logs are ignored.	Your text logs are debugging output or metadata that should not be part of the evaluated response

Set the strategy at construction time or override it per evaluate() call via task.evaluate(config, merge_strategy="traces_only").

9. Step-Specific Evaluation¶

TaskEval supports both global and step-level scoping for logs, templates, and rubrics. This enables per-phase analysis of multi-step agent workflows.

When you call evaluate() without a step_id, TaskEval:

1. Runs global evaluation against all global-scope logs and criteria
2. Automatically evaluates every step that has logs, templates, or rubrics defined

Results are structured as:

• result.global_eval: a StepEval containing global verification results
• result.per_step: a dict[str, StepEval] mapping step IDs to their evaluation results

To evaluate only one step, pass step_id to evaluate().

See the workflow for step-scoped evaluation examples.

10. Result Objects¶

evaluate() returns a TaskEvalResult that wraps all evaluation outcomes. Each scope (global or per-step) is represented by a StepEval, which stores VerificationResult objects keyed by question ID.

Method on TaskEvalResult	Returns
summary()	One-line summary: "2/3 template verifications passed | 4/5 rubric traits passed"
summary_compact()	Compact one-liner with task ID and success rate
display()	Formatted multi-line report with all verification details
export_json()	Full results serialized as a JSON string
export_markdown()	Results formatted as Markdown

StepEval provides get_summary_stats() for aggregate statistics (traces passed, template verification counts, rubric trait counts, success rate) and aggregate_rubric_results() for averaging rubric scores across replicates. For replicate support, set replicate_count on your VerificationConfig.

11. Next Steps¶

• TaskEval workflow: step-by-step guide with complete code
• Answer templates: writing templates for correctness evaluation
• Rubrics: defining quality traits
• Verification pipeline: the 13-stage pipeline TaskEval routes through
• Evaluation modes: template_only, rubric_only, template_and_rubric