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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond them: letter text is never stored and the subject is shown live, plus the days default of 90 with a max of 365 and the candidate-list fallback for ambiguous queries. These are solid additions but the bar is lower given full annotation coverage.

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?

The core scope is front-loaded in the first sentence, followed by the add_person_suggestion handoff and then the parameter rules. Quoted content-type names aid scanning, though the paragraph is dense and could be split for readability.

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 does the work of describing return shape ('each suggestion has an id and accepted'), and with no annotations on return values it states the source domains and the live-subject behavior. The one real hole is the undocumented 'limit' parameter; otherwise an agent has enough to call and interpret the tool.

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 0%, so the description must carry all parameter meaning. It explains contact_id vs query and the ambiguity fallback, and gives days semantics (look-back, default 90, max 365), but the 'limit' parameter is never mentioned anywhere, leaving one of four parameters unexplained.

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 the resource precisely (suggestions about one person: letters, meetings, forwards, upcoming_meetings) and scopes it to the caller's own contact book and readable mailboxes. It is clear what the tool returns, though the verb is expressed indirectly ('offered as SUGGESTIONS') and it does not distinguish itself from adjacent readers like person_brief or get_person.

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 gives explicit next-step routing ('put one into the timeline with add_person_suggestion (only when the person asks)') and a disambiguation rule for the lookup selector ('contact_id' or 'query'; ambiguous → candidates, ask which one). It stops short of stating when to prefer this over other person-context tools.

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