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

Annotations declare idempotentHint=true and destructiveHint=false, and the description usefully corroborates and extends that: "your one reaction" discloses that a new reaction replaces the previous one, and "none to clear it" describes the removal path. It still omits auth/rate-limit context and whether the post author is notified, but it adds real behavioral context beyond the structured hints.

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?

A single sentence with the mutation and its scope front-loaded, and the enum parenthetical placed last. No filler or repetition beyond the necessary value list.

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 3-parameter mutation with partial schema coverage and no output schema, the description covers the core action but is silent on what the caller gets back (updated reaction state?) and on failure modes such as an invalid or expired token. The annotations carry the safety profile, so this is minimum-viable rather than deficient.

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 67%, so id and token are already documented in the schema. The description only restates the enum values that the schema already lists and adds no meaning about reaction semantics or how post ids are formatted. Baseline 3 is appropriate given a partial coverage gap.

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 ("Sets your one reaction to a post") and enumerates the exact reaction domain, which cleanly separates it from rssa_board_post, rssa_board_edit, and rssa_board_delete. An agent can identify the operation without opening the 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?

Usage is implied by the enum semantics ("none to clear it") but there is no explicit when-to-use guidance, no prerequisites, and no named alternative among the nine sibling tools. Adequate but leaves an agent to infer the trigger conditions.

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