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 is covered. The description adds value beyond that by disclosing the shape of the result (key kind, parameters, examples) and the important edge behavior that an empty query returns the entire reference — a detail an agent would otherwise only learn by calling it.

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 short sentences, front-loaded with what the tool returns, followed by how to query and the no-argument case. Every clause carries information and there is no filler.

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 must explain what comes back, and it does so concisely (routes plus kind, parameters, examples). For a single optional parameter, read-only lookup tool this is nearly complete; the only gap is no hint about the volume or size of a full unfiltered dump.

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 single property already says 'Route or words. Omit for everything.' The description reinforces this with concrete examples ('POST /orders', '/esims/{id}/topups', 'webhook'), which is mildly helpful but largely restates the schema, so the baseline of 3 applies.

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 states a specific resource and return content: 'Exact partner API routes with key kind, parameters and examples', which tells an agent this is a route-reference lookup rather than generic document retrieval. It does not explicitly contrast itself with the doc-oriented siblings (search_docs, read_doc, list_docs), so an agent must infer the boundary from the word 'routes'.

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?

Usage is implied through the query syntax: use route paths for exact lookups, words for topical search, and omit the argument to get everything. There is no explicit statement of when to prefer this over search_docs or read_doc, nor any caution about the cost of an unfiltered query.

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