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

Annotations already provide idempotentHint and destructiveHint, and the description aligns with these by stating 'Safe to repeat.' It adds value beyond annotations by detailing the exact scope of deletion ('Nothing else is deleted: the article and its comments are untouched'), the fact that removing one type doesn't affect others, and the API key requirement. This gives a fuller behavioral picture.

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 description is three concise paragraphs, front-loaded with the primary action, then expanding into edge-case behavior and usage hints. Every sentence adds value: no fluff, no repetition of schema details, and the structure is logical (action, scope, safety, prerequisite).

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 tool with two simple parameters and no output schema, the description covers all essential aspects: what it does, what it doesn't affect, idempotency, authentication requirement, and a recommendation to check current state. It sufficiently prepares an agent to use the tool correctly without needing additional implicit knowledge.

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?

The input schema has 100% coverage with clear descriptions for both parameters (type enum and article_id UUID). The description's mention of 'Removes exactly the type you name' reinforces but does not add new semantic meaning beyond the schema. Since the schema already documents the parameters thoroughly, a baseline score of 3 is appropriate.

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 clearly states the action: 'Withdraw one reaction the authenticated account previously left on an article.' It specifies the resource (reaction) and the exact scope (one reaction), and distinguishes from sibling tools like add_reaction and get_reactions by explicitly noting it removes only the named type and leaves others intact.

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?

The description provides clear context on when to use the tool (to withdraw a reaction) and gives an alternative: 'Call get_reactions first if you need to know what is currently set.' It also implies when not to use it (e.g., for adding reactions, use add_reaction, though this isn't explicitly stated but is inferable from sibling names).

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