get_metro

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

No annotations are provided, so the description carries the full burden for behavioral disclosure. It states the tool returns metro stations and lines with IDs, implying a read-only operation, but it does not explicitly mention side effects, permissions, or response structure. While minimal, it does not contradict any annotations (none exist) and the read-only nature is implied by 'get'.

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 concise sentences with no filler. The first sentence states the core function and scope, the second explains the purpose. Information is front-loaded and every word earns its place.

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 simple lookup with one optional parameter and no output schema, the description provides enough context for an agent to call it correctly. It explains the purpose and scope. It could optionally mention the response format or authentication requirements, but these are not critical for a straightforward get operation given the simplicity.

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?

The schema description for city_id fully explains the parameter and its optionality (including examples like 1=Moscow), achieving 100% coverage. The tool description repeats this information without adding new meaning. Since the schema already documents the parameter, the description's contribution is redundant but not harmful.

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 clearly states the tool retrieves metro stations and lines with IDs, for a specific city or all cities. It also specifies the intended use ('find metro IDs for the search_vacancies metro filter'), which distinguishes it from other lookup tools like get_areas or get_dictionaries. Verb and resource are specific and 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?

The description provides explicit context for when to use the tool: to obtain metro IDs for the search_vacancies metro filter. It indicates the optional city_id parameter and the behavior when omitted. However, it does not mention when not to use it or alternatives, though the named use case is sufficient for most scenarios.

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