react

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

Annotations already indicate the tool is read/write, non-idempotent, and destructive, so the description doesn't contradict them. The description adds context about target types, but it does not disclose behavior such as whether adding an existing reaction replaces it, whether removal is idempotent, or what the response contains. Given annotation coverage, a mid-range score is appropriate.

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 concise sentences with no filler. The action and target types are front-loaded, and the pointer to targetType/targetId is efficient and directly useful.

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?

The description, combined with a complete input schema and output schema, covers the essential information an agent needs to select and invoke the tool. It could mention the operation default or enum, but the schema already documents those details, so nothing critical 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 description coverage is 100%, so the baseline is 3. The description adds minimal value beyond the schema by restating targetType/targetId roles, but it does not introduce new parameter details or usage nuances.

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 action—'Add or remove an emoji reaction'—and names the resource types explicitly (thread, comment, conversation message). It clearly differentiates the tool from siblings like reply, delete-object, or update-object by focusing on emoji reactions.

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?

Provides clear context on when to use the tool: whenever an emoji reaction needs to be added or removed on a thread, comment, or message. It does not explicitly name alternatives or exclusions, but none of the sibling tools target reactions, so the usage scope is adequately defined.

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