Add Reaction

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

The description is consistent with the annotations (readOnlyHint=false aligns with 'Add...'). It adds content-type constraints (emojis, short text, max 16 characters) and the lightweight-response framing. However, the annotations are minimal, and the description does not disclose repetition behavior (what happens if the same reaction is added twice), permission needs, or return value, leaving some behavioral gaps for a mutation tool.

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?

Three short sentences with the action verb front-loaded. The second sentence on content format partially repeats what the schema's content property already states, which is minor waste, but overall the definition is efficiently sized and readable at a glance.

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 simple, well-documented action (4 required params, all clearly described in schema, no output schema), the description covers the purpose and use case adequately. The schema handles parameter semantics, so the only real gaps are unstated idempotency behavior and return-value expectations, which are minor for a lightweight write action.

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% — every parameter (content, comment_id, card_number, account_slug) has a detailed schema description including formats and examples. The tool description largely duplicates the schema's content details (emoji examples and the 16-character limit). With full schema coverage, the baseline of 3 applies; the description adds no new parametric meaning.

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 opens with a specific verb+resource construction: 'Add an emoji reaction to a comment.' It clealy distinguishes this from sibling tools like fizzy_remove_reaction (removal) and fizzy_create_comment by framing reactions as 'quick... responses without writing a full reply.' The scope is precise and no ambiguity remains about what operation this performs.

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?

'Use this to quickly acknowledge or respond to comments without writing a full reply' provides a clear context for when the tool applies. It implies when-not-to-use (when a substantive reply is warranted) but never names alternative tools explicitly, so an agent must infer that fizzy_create_comment is the fallback.

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