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

No annotations are present, so the description carries the burden. It discloses the important constraint that the spec must be self-contained (no external $ref resolution). Returns findings (empty when valid). While it does not detail the exact format of findings or error handling, for a validation tool this is reasonably transparent.

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 very concise: four sentences, each earning its place. It starts with the main purpose, then usage guidelines, then a constraint. There is no wasted text. Structurally excellent.

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?

Given the tool has one parameter, no output schema, and no annotations, the description covers the key aspects: what it does, when to use it, input format (YAML/JSON), a constraint (self-contained), and expected output (findings, empty if valid). It does not explain the structure of findings or error messages, but for a validation tool this is adequate.

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?

The single parameter 'spec' is fully described in the schema (100% coverage). The description adds 'Pass the spec as YAML or JSON' which is redundant with the schema. It also mentions the self-contained constraint, which is about the spec content rather than parameter semantics. Hence, the description adds little beyond the schema, so baseline 3 is appropriate.

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?

Purpose is clearly stated: 'Validate a single OpenAPI specification against the OpenAPI and JSON Schema rules.' It uses a specific verb (validate) and resource (single OpenAPI spec). It also distinguishes itself from siblings by explicitly mentioning that for comparing two specs, one should use other tools.

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?

Explicit usage guidance is provided: 'Use this when you have one spec and want to check it is well-formed.' It also gives alternatives for different needs: 'For comparing two specs, use oasdiff_breaking_changes, oasdiff_changelog, or oasdiff_diff instead.' This is excellent.

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