line_link_richmenu

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

Annotations already declare it non-read-only, idempotent, non-destructive. The description adds real context beyond that: it is a per-user override rather than a global change, and passing null reverts to the default menu. It does not discuss permissions or error behavior, but the override semantics are the key hidden trait.

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?

Two sentences, zero padding, with the primary action front-loaded and the null edge case as the follow-up. Every clause earns its place.

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 2-required-param mutation with no output schema and no annotations covering the override behavior, the description supplies the essential per-user/default interplay. Return values are correctly omitted since no output schema exists, though permission or failure behavior is unmentioned.

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 carries the burden, and it does explain the non-obvious richMenuId null semantics that the schema only hints at via the nullable type. userId's U-prefix format is left to the schema pattern, so it is not fully compensated.

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 ('Show a specific Rich Menu to one user'), and the scoping to a single user distinguishes it from line_richmenu_list. It never names a sibling explicitly, so differentiation is implied rather than stated.

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 when-to-use context ('e.g. after a role change') and the alternative action for the null case (removing the per-user menu so the default shows). No explicit when-not or named alternative tool, but the trigger condition is clear.

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