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

Annotations already mark the tool as read-only and idempotent, so safety context is covered. The description adds valuable behavioral nuance: case-insensitive partial matching, that one name usually covers both sides of the street under different IDs, and that the routes list disambiguates them. This goes beyond the structured metadata.

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, all high-value and front-loaded: primary behavior, clear usage instruction, edge-case warning, and a direct alternative. No filler or repetition of schema details.

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?

Given the annotations, output schema, and schema descriptions, the description covers everything needed to invoke the tool correctly. It explains when to use it, what it returns, how to interpret ambiguous results, and which sibling to prefer in a different scenario.

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%, so the baseline is 3. The description adds meaning beyond the schema by clarifying that the query supports Ukrainian and English transliteration and case-insensitive partial matching. It also provides realistic examples in both languages, strengthening an agent's ability to form valid queries.

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 a specific verb and resource: 'Finds stops by name' and specifies matching behavior (Ukrainian/English, case-insensitive, partial match) plus the returned data (ID, coordinates, routes). It explicitly distinguishes itself from the sibling get_stops_around_location, making selection unambiguous.

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?

It tells the agent exactly when to use this tool: as the first step when the user names a stop and a stop ID is needed for get_stop_realtime or find_routes_between. It also states the alternative condition: use get_stops_around_location when coordinates are available instead of a name.

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