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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuine behavioral value beyond that: what each level returns (modules/pages with short descriptions and endpoints; OpenAPI file with method, url, headers, params, body example, sample responses) and the progressive-disclosure pattern. Missing only pagination/size or failure-mode context.

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?

Four sentences, each doing distinct work: entry point, mid-level navigation, endpoint detail retrieval, and a usage constraint. The no-argument case is front-loaded so the agent sees the default behavior first. No redundancy with the schema text.

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 no output schema, the description carries the return-value burden and does so: it describes what a top-level listing contains, what nested listings link to, and the exact fields in the OpenAPI endpoint response. For a single-optional-param read-only tool this is complete enough to invoke correctly without experimentation.

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 100% and the parameter's own description already covers accepting a full link from a listing or a bare path, and omitting it for top level. The description reinforces this but adds no syntax or format detail the schema lacks. Baseline 3 applies since the schema does the heavy lifting for a single optional parameter.

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 (Browse) and resource (MSG91 API docs) plus the distinguishing mechanic: one level at a time, progressive disclosure. An agent immediately knows it's a navigational fetch tool. It doesn't explicitly name search_msg91_docs or quickstart-msg91 as the alternatives, so the differentiation from siblings is inferred rather than stated.

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?

Gives concrete when-to-use rules per argument shape: omit `path` for the top level, pass a module/page link for its contents, pass a `.openapi.yml` link for endpoint detail. The closing 'Fetch only the level you need' is an explicit usage constraint. It stops short of saying when to prefer search_msg91_docs instead.

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