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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is partly covered. The description adds real context beyond that: what the response contains ('saved guest details, including cleared values'), the auth/membership requirement, and the boundary of what the write can touch. It never explicitly warns that supplying empty strings erases stored values, which is the main remaining gap given destructiveHint=true.

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?

Four sentences, all front-loaded: purpose first, then required identifier, then return behavior, then exclusions and auth. Each sentence carries distinct information, though the return-value sentence is close to filler since it could be inferred.

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 usefully states what comes back, and it covers prerequisites, mutation scope, and field exclusions for a 10-parameter mutation tool. The one omission is an explicit warning that clearing fields is irreversible for those values, despite destructiveHint=true.

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 description coverage is 100%, so every parameter already carries its own documentation (including the nuanced 'empty string clears it' and language-clearing semantics). The description only summarizes the updatable field families and notes guest_id is required, adding little beyond the schema; baseline 3 applies.

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 (updates) and resource (a wedding guest) plus the exact field families affected: name, contact, RSVP, communication preferences, language. It also scopes the target with 'already recorded as 13 or older in the selected wedding', which separates it from add_my_guest and remove_my_guest without opening either 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?

Gives clear when-not conditions ('cannot change age bands, guest notes or dietary details') and prerequisites ('Requires sign-in and an Aisle membership'), which route the agent away from this tool for those cases. It stops short of naming the alternative tool for the excluded fields, so it falls just under the explicit-alternatives bar.

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