hermes-rubric

Evidence-first assessment for agent outputs and applications.

Hermes turns an artifact into cited evidence, dimension scores, honest coverage facts, and caller-controlled feedback. It measures and explains; your application decides what to do next.

from hermes_rubric import FeedbackPolicy, assess

result = assess(
    target=agent_output,
    intent="Answer accurately and support material claims with checkable evidence.",
    context=task_context,
    target_type="agent-output",
    backend="openai-sdk",
)

print(result.aggregate)
print(result.coverage.status)
print(result.feedback(FeedbackPolicy(minimum_score=7)).to_prompt())

The same call can sit inside LangChain, the OpenAI Agents SDK, Semantic Kernel, PydanticAI, a bespoke loop, a notebook, CI, or a plain Python service. Those frameworks are not core dependencies, and Hermes does not run an agent loop for you.

Install

The base package requires Python 3.10 or newer and PyYAML:

pip install hermes-rubric

For the example above, install the OpenAI extra and set OPENAI_API_KEY:

pip install "hermes-rubric[openai]"

You can instead use local Ollama, Claude Code, another built-in backend, or a backend plugin. Automatic selection checks authenticated Claude Code first, then local Ollama; cloud providers are always explicit opt-ins. See Backends.

One transaction, three evidence-first stages

Hermes keeps the measuring process separate from runtime policy:

1. Synthesize a task-specific rubric, load a bundled deterministic template, or accept a caller-provided frozen rubric.
2. Collect and validate citations for each dimension.
3. Score only against accepted evidence, applying the existing hedge, no-evidence, and source-authority clamps.

The returned AssessmentResult has attribute access plus to_dict() and to_json(). Its JSON preserves the established CLI keys and adds a versioned schema and coverage report.

payload = result.to_dict()

assert payload["schema_version"] == "1.0"
print(payload["evidence_citations"])
print(payload["per_dim_scores"])
print(payload["receipt"])

The aggregate is a signal, not a verdict.

Choose the measuring stick

Synthesize from intent and context when the criteria should be task-specific:

result = assess(
    target=answer,
    intent="Evaluate whether this answer is accurate and well-supported.",
    context="The answer must distinguish observation from inference.",
    target_type="agent-output",
)

Reuse a frozen rubric when runs must share the same dimensions:

import json
from hermes_rubric import assess

with open("rubric.json") as handle:
    frozen_rubric = json.load(handle)

result = assess(target=answer, rubric=frozen_rubric)

Use a bundled deterministic artifact class for common publishing surfaces:

result = assess(target=readme_text, artifact_class="repo-readme")

Bundled classes are social-post, show-hn-post, linkedin-post, outreach-email, and repo-readme.

Coverage is part of the result

Version 1.1 uses the existing UTF-8-safe prefix strategy for evidence collection. The default target window is 8,000 bytes. Hermes reports coverage.status as complete or partial, includes visible and total byte facts when they are knowable, discloses directory source limits, and lists plain-language limitations.

if result.coverage.status == "partial":
    for limitation in result.coverage.limitations:
        print(limitation)

partial means relevant material may not have been inspected. It must not be translated into “the evidence is absent.” Full chunked retrieval is a later engine capability, not a v1.1 claim.

Feedback without hidden policy

Hermes distinguishes three next-step types:

• quality_gap: inspected evidence supports a score below a threshold you supplied.
• evidence_gap: accepted evidence is absent or hedged.
• coverage_gap: the relevant material may not have been inspected.

No pass/fail threshold is built in. FeedbackPolicy(minimum_score=...) is caller policy, and to_prompt() only creates deterministic instructions—it never mutates a runtime or retries an agent. A coverage-only gap asks for wider inspection, not an automatic rewrite.

File and CLI workflows

Use assess_path() for a file or directory:

from hermes_rubric import assess_path

result = assess_path(
    "paper.md",
    intent="Evaluate publication readiness.",
    context_path="STYLE-GUIDE.md",
    target_type="paper",
)

The CLI is the equivalent file and automation surface:

hermes-rubric \
  --intent "Evaluate publication readiness" \
  --context STYLE-GUIDE.md \
  --target paper.md \
  --out result.json

Existing flags, output keys, and stage exit codes remain available. See the full CLI reference.

Async wrappers keep synchronous providers off the event loop:

from hermes_rubric import assess_async

result = await assess_async(answer, rubric=frozen_rubric)

They use asyncio.to_thread; cancellation cannot interrupt a provider call already running in its worker thread.

When to use Hermes

Use it when:

• an agent or application needs cited, inspectable assessment rather than a raw judge score;
• weak or missing evidence must remain visible;
• the same assessment contract should work across different runtimes;
• receipts and frozen rubrics matter for reviewing repeated runs.

Use a deterministic validator instead when the rule can be expressed exactly. Do not use Hermes as proof of factual truth, as a compliance certification, or as an automatic release decision. If the artifact is longer than the inspected window, review coverage before acting on missing evidence.

Documentation

• Quickstart
• Python API
• Architecture and product boundary
• Adapter contract
• Backends
• CLI
• Benchmarks and evidence limits
• v1.1.1 release notes
• v1.1.0 release notes

Contributing

git clone https://github.com/hermes-labs-ai/hermes-rubric
cd hermes-rubric
pip install -e ".[dev]"
pytest

The adversarial tests in tests/test_adversarial.py are release gates. See CONTRIBUTING.md.

License

Copyright 2026 Hermes Labs. Licensed under Apache-2.0. See LICENSE.