Google: Token & scopes

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuine context beyond that: it reveals the diagnostic role (403 triage) and that the output distinguishes write from read-only token modes. It doesn't mention credential/auth prerequisites for the call itself, which keeps it from a 5.

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?

A single sentence, front-loaded with what it reports and ending with the operational trigger. Every clause earns its place, with no filler or restatement of the title.

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?

With no parameters, no output schema, and read-only annotations, the description supplies enough: what is reported (token mode, scopes) and when to call it. A hint about the response shape would have fully closed the gap left by the absent output schema.

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 takes zero parameters, so the schema carries no semantic burden and the baseline of 4 applies. Nothing in the description is needed to explain inputs, and it correctly doesn't waste words on them.

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: it shows which refresh token is active (write vs read-only) and which OAuth scopes it carries. No sibling tool in the GTM/GA4 list does anything similar, so an agent can identify this as the credential-inspection tool without opening the schema.

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 states an explicit trigger: 'first check when a write tool fails with 403.' That tells the agent both when to reach for it and how it relates to the mutation siblings that might fail. The guidance is concrete rather than implied.

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