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

Annotations already cover read-only and closed-world safety, so the bar is lower. The description adds real behavioral context: the response is the full public detail, and missing/unlisted units are reported plainly rather than erroring ambiguously. Pagination and output shape are not described, but no output schema exists so some ambiguity remains.

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?

Two tight sentences with the resource and scope front-loaded. The phrase "plus how to ask about it" is slightly cryptic but does not bloat the definition.

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?

For a one-parameter read tool with full annotations and no output schema, this covers what the agent needs: what is returned (full public detail) and how unlisted units behave. Only the response format/field list is left unspecified.

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 coverage is 100% and the single parameter is fully documented in the schema, including the example slug and its origin in search_buses. The description's "listing URL or slug" merely restates the schema, so baseline 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?

States a specific verb-and-resource: fetch one listed bus in full public detail, keyed by URL or slug. It is clearly a single-record lookup distinct from search_buses, though it doesn't explicitly name that sibling.

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?

"by its listing URL or slug" implies you need a listing identifier from search_buses, which is useful routing context. But there is no explicit when-to-use/when-not statement and no mention of get_bus_category or request_bus by name, so the guidance is only implied.

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