gsc_list_sites

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

With no annotations to carry the safety profile, the description fully covers behavioral context: it details the three permission levels, what each can and cannot do (e.g., 'siteRestrictedUser -- performance data only, URL inspection blocked'), and warns that unverified users will cause most calls to fail. This goes well beyond a simple 'list' statement.

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 front-loaded with the primary action, then adds the 'call this first' guidance, then the critical format caveat, then a compact permission-level legend. Every sentence earns its place and there is no filler or repetition of schema content.

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 zero-parameter discovery tool with an output schema, the description is complete: it explains why to call it first, what the returned identifiers look like, how permission levels affect subsequent tool behavior, and the failure mode for unverified users. Nothing needed for correct invocation is missing.

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 and the schema is an empty object, so there is nothing for the description to explain. The baseline for 0-param tools is 4, and the description appropriately avoids inventing parameter details.

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 every Search Console property this credential can read, with the permission level held on each.' This clearly defines scope and output without ambiguity, and distinguishes this discovery tool from the analytics/sitemap/inspection siblings.

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 explicitly says 'Call this first,' establishing this as the prerequisite step for other GSC tools. It also explains that the returned site_url strings are 'the exact values every other tool expects,' giving the agent a concrete reason and workflow context for invoking it.

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