Update partner

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

Annotations already declare readOnlyHint=false and destructiveHint=true; the description adds value by clarifying the change is reversible ('they stay reachable either way') and stating the server-side side effect plus the shared_with_me precondition. It does not contradict the annotations, though the mild, reversible nature of the toggle sits in mild tension with destructiveHint=true and could have been called out more explicitly.

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 effect and the precondition before the Args/Returns block, with no wasted sentences. The Returns line is mild redundancy given an output schema exists, and the Args restate parameters that the body already implied.

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?

For a two-parameter mutation with an output schema, everything an agent needs to call it correctly is present: what changes, the reversibility guarantee, the eligibility precondition, and confirmation of a server-side write. Nothing material 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?

Schema coverage is 0% — bare 'User Id' and 'In Timeline' — so the description must carry the load, and it does: user_id is 'the partner whose setting changes' (constrained elsewhere to shared_with_me), and in_timeline is spelled out as mix-into-timeline true vs keep-separate false. This resolves real ambiguity a bare boolean label leaves open.

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 plus resource and the exact effect: flipping a partner's visibility flag so their photos appear in (or stay out of) the main timeline. The parenthetical 'they stay reachable either way' defines scope precisely and distinguishes this from remove_partner or update_person among the siblings.

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 a concrete eligibility condition: only works on a partner in shared_with_me, with the reasoning (the flag controls how THEIR photos appear in THIS timeline). It stops short of naming an alternative tool or an explicit when-not-to-use case, so it is clear context without full routing guidance.

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