behavior_diff

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description must carry the full behavioral burden. It discloses the computed result set (coverage, missing/extra exports) and the comparison nature implies a read-only operation, but it does not state permissions, side effects, or error behavior. This is adequate but leaves meaningful behavioral gaps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single compact sentence with the core action front-loaded: 'Diff two API-surface dumps.' The colon-delimited output summary is efficient. The phrase 'THE key progress metric' adds useful emphasis but is slightly evaluative rather than purely operational.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a four-parameter tool with 0% schema description coverage and no annotations, the description does too little on the input side. It does not explain what baseline, current, out, or workspace should contain, nor does it state any operational constraints. The output schema covers return values, but the description remains incomplete for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% across four parameters. The description hints that two inputs are the reference and rebuilt dumps, which loosely maps to 'baseline' and 'current,' but it never names them or explains 'out' and 'workspace.' Two of four parameters are effectively undocumented in both the schema and description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb and resource: 'Diff two API-surface dumps (reference vs rebuilt build).' It also states the output content, 'per-module export coverage, missing/extra exports,' which makes the purpose intelligible without opening a schema. It does not explicitly contrast itself with sibling tools like dump_api_surface or compat_report, so it falls short of the top score.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the scenario: compare a reference dump against a rebuilt build to measure compatibility progress. However, it never explicitly says when to call this instead of alternatives such as dump_api_surface or compat_report. The usage context is inferable but not clearly specified.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.