Token identity and scopes

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context by enumerating the returned metadata (scopes, expiry, consent expiry, UID) and the failure mode it diagnoses. No auth prerequisites or rate limits are stated, keeping it below 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?

Two sentences, zero waste. The return contents are front-loaded and the diagnostic use case follows immediately. Every clause 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?

With no output schema, the description carries the burden of explaining return values, and it does so by listing the four fields. For a zero-parameter read-only introspection tool this is nearly complete; only the precise format of the returned values is left unspecified.

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 there is nothing for the description to disambiguate. Baseline 4 applies; the description correctly makes no parameter claims.

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?

States a specific verb and resource (returns the access token's granted OAuth scopes) and enumerates exactly what comes back: scopes, expiry, consent expiry, and account holder UID. This clearly distinguishes it from the account/transaction/payee siblings, which all deal with banking resources rather than token metadata.

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?

Explicitly names the triggering scenario: 'Use this to diagnose 403 errors (missing scope).' That tells the agent precisely when to reach for it. It stops short of naming any alternative tool for the same diagnostic purpose, but no obvious sibling competes here.

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