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

With no annotations, the description carries the full burden and does reasonably well: it enumerates what is compared (including 'required toggle' and retype detection) and states the return shape. It does not mention whether specs are validated, size limits, or error behavior on malformed input, which are the remaining behavioral gaps for a parsing tool.

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?

Three tight paragraphs, front-loaded with the core action, then usage, then the full diff scope and return shape. Every sentence adds information; no filler or restatement of the tool name.

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?

An output schema exists, so the return format need not be described, though the description does so anyway as a convenience. For a two-param, computation-only tool with no annotations, the description covers purpose, scope, input format, and output well. Only minor gaps remain (input validation, error conditions).

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% — the schema provides only titles like 'Old Spec' and 'New Spec'. The description compensates by stating 'Both arguments are the OpenAPI spec as a JSON or YAML string,' which is the critical format information the schema lacks. It does not clarify ordering semantics (which spec is old vs new) beyond parameter names.

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?

States a specific verb (compare) plus the resource (two OpenAPI 3.x specs) and the classification output (breaking/non-breaking/info). It also enumerates the diff surface (paths, operations, parameters, request bodies, responses, response-body schema fields), which makes it unmistakable relative to any sibling. No other tool in the list performs spec comparison.

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?

Explicitly frames the use case: 'Use this when you want to know if a candidate OpenAPI spec change is safe to ship or will break existing clients.' That gives a clear triggering condition. It stops short of naming when-not-to-use or an alternative, but no sibling overlaps this function, so the omission is minor.

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