list_sites

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

With no annotations provided, the description carries the full burden, and it does so thoroughly. It discloses response structure, nested stats behavior when date_range is supplied, units for each metric, timezone approximation caveats, and free-plan implications. This goes well beyond a minimal listing tool description.

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 long but every sentence earns its place. It front-loads the core purpose and response format, then adds the hobby-plan caveat, metric units, and timezone precision caveat in a logical order. There is no filler or repeated schema information.

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?

There is no output schema, so the description must fully document the return shape and behavior, and it does. It covers the site object, nested stats, metric semantics, units, plan implications, and the recommendation to use query_stats for precision. An agent has enough context to call the tool and interpret results correctly.

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 input schema already provides 100% coverage for date_range, so the baseline is 3. The description adds meaningful semantics: nested stats are never flat, units are defined, and timezone accuracy is called out as approximate. This clarifies interpretation beyond the schema's raw parameter text.

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 opens with a specific verb and resource: 'List the sites this API key can read.' This clearly defines the operation, the scope (API-key-readable sites), and distinguishes it from other site-related tools by emphasizing the listing and scoping behavior.

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 gives practical routing guidance: it explains that site_id should be used with other tools, that hobby sites require the get_tracking_snippet script, and that query_stats should be used for timezone-exact numbers. It stops short of explicitly enumerating when not to use list_sites versus each sibling, but the context is strong.

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