list_available_metrics

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently states the operation is a read-only listing ('List all') and specifies the return format (list of objects with api_name and description). This exceeds baseline by adding output structure, though it does not mention potential side effects (unlikely for a listing) or auth requirements.

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?

The description is two short sentences, front-loaded with the core purpose and followed by a clear 'Returns' line. Every word earns its place, with no fluff or repetition of the tool name beyond what's necessary for clarity.

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?

The tool is simple with no parameters and no output schema, but the description clearly explains the return value structure (list of metric objects with api_name and description). This fully covers what an agent needs to know to invoke and interpret results. Sibling tools are for different resources, so context is adequate.

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 tool has zero parameters, so the baseline is 4 as per rubric. The description does not need to add parameter details, and it avoids unnecessary explanation. The schema is empty, so no parameter coverage issues exist.

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 lists all available GSC metrics with descriptions, using a specific verb ('List') and resource ('GSC metrics'). This distinguishes it from the sibling tool list_available_dimensions, which lists a different resource (dimensions).

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 implies usage by describing exactly what the tool returns, but it does not explicitly provide when-to-use guidance or mention alternatives. It lacks any exclusion statements, such as 'for dimensions, use list_available_dimensions instead', so guidance is implied rather than explicit.

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