React to a post

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

With no annotations provided, the description carries the disclosure burden. It clearly states the tool performs an additive write action ('Leaves a reaction'), which is transparent about mutating behavior. However, it does not disclose whether a reaction replaces an existing one, whether repeated calls are idempotent, or what side effects occur.

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 a single, tightly composed sentence that front-loads the action and target, then lists the allowed values. Every word earns its place, and there is no redundant filler.

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 tool is simple, with only two required parameters and no output schema, so the description covers the essentials of what and where. However, it omits the return behavior, error conditions, and whether the reaction is additive or replacing, leaving moderately important operational context 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 0%, so the description needed to compensate. It only restates the reaction enum already present in the schema and gives minimal context for postId ('on a post'). It does not explain the meaning of each reaction, postId format, or behavior for invalid inputs, leaving the parameter semantics under-specified.

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 states a specific verb ('Leaves a reaction') and a specific resource ('a post'), and enumerates the exact reaction types. This distinguishes it from the sibling react_to_message by explicitly scoping to posts, so there is no ambiguity about the tool's core function.

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 implies the tool is used when you want to react to a post, but it gives no explicit guidance on when to prefer it over alternatives like react_to_message or comment. It provides only implied usage context, not explicit selection criteria.

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