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

Goes well past the annotations (readOnly/idempotent/non-destructive) by disclosing error-equivalence semantics that prevent enumeration, the exact field set returned, the meaning of the 'defaulted' contact-preference list, and that guest notes and dietary details are excluded. These are behavior traits an agent could not infer from structured fields.

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?

Three dense sentences, front-loaded with the core purpose, then return contents, then edge-case/auth behavior. No filler or repetition 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 output schema, the description enumerates the returned fields itself, and it adds auth requirements and error behavior for a single-entity read tool. An agent has everything needed to call it correctly and interpret the result.

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?

Schema coverage is 100%, so guest_id and wedding_id are already documented in the schema, including the multi-wedding requirement. The description adds only incidental meaning ('selected wedding', implicit 13+ eligibility for guest_id), so the schema does the heavy lifting.

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 one identified guest') and constrains scope to guests recorded as 13 or older in the selected wedding. The 'one identified' framing clearly separates it from list_my_guests without needing to name the sibling.

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?

Gives concrete preconditions and routing context: requires sign-in, and missing/other-wedding/under-13/unconfirmed-age lookups all collapse to the same not-found result. It does not explicitly name list_my_guests as the alternative for enumeration, so it stops short of full when/when-not guidance.

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