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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile needs no restatement. The description adds real value beyond that by describing what each mode returns at a content level (brief method/path/summary vs. one endpoint's parameters and body), though it says nothing about result volume or pagination when returning every endpoint.

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?

A single sentence that front-loads the resource identity and then walks the modes in increasing specificity, using backticked parameter names as anchors. No filler, no repetition of the title.

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?

With three optional params and an output schema present, the description covers everything needed to choose a mode correctly. Minor gaps remain around the volume/shape of the unfiltered listing and the accepted format of `path`/`method`, which an agent would have to guess on first call.

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%, so the description must carry all parameter meaning — and it does explain the role of all three (`search`, `path`, `method`) plus the path+method combination. It does not specify expected formats (path syntax, HTTP method casing) or whether `method` alone is meaningful, leaving a residual ambiguity for a 0%-coverage schema.

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 the resource precisely ('The REST API's reference (OpenAPI)') and enumerates the three operating modes with their parameter triggers. It implicitly separates itself from the sibling api_request by framing this as documentation lookup, but never names or contrasts that sibling explicitly, so it falls short of a 5.

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?

Each mode is given a clear use condition: no arguments for a full brief listing, `search` for word-based narrowing, `path` (+`method`) for a single endpoint's detail. What's missing is routing guidance toward alternatives (e.g., when to use api_request to actually call an endpoint rather than read about it), so there are no stated exclusions.

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