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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds real value beyond them: it discloses the cost profile ('Cheap, a few small DB reads'), the error-prevention benefit against 401/402, the PAT-scope context behavior when called via MCP, and the semantic distinction between youAre and persona name.

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?

Front-loaded with the purpose and the returned data, then the youAre clarification, then the usage rationale. It is longer than strictly minimal and the youAre sentence is dense, but each sentence contributes routable value rather than filler.

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 carries the full burden of describing return values, and it does so field-by-field (identity, org context, feature gates, PAT scope, conversation id, youAre). Nothing an agent needs to interpret the result or decide to call this first 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 takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The field-level detail it provides describes return values rather than inputs, which is appropriate.

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 ('Self-introspection. Returns the calling agent's identity...') and enumerates exactly what the response contains. It explicitly distinguishes itself from its siblings by naming describe_capabilities (tool surface) and describe_schema (entity shapes), so an agent can route between them without opening a 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?

Provides clear when-to-use guidance: 'Grounding a session on this first is what stops subsequent tool calls trial-and-erroring 401/402,' and directs persona/identity questions to the youAre field. It names the companion tools but stops short of stating an explicit when-NOT-to-use condition, keeping it just shy of a 5.

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