fc_send_chat_message

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the action (send) but doesn't reveal any behavioral traits: no information on permissions required, rate limits, whether the message is editable/deletable, response format, or error conditions. For a mutation tool with zero annotation coverage, this leaves significant gaps in understanding how it behaves beyond the basic action.

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, efficient sentence with zero wasted words: 'Send a message in a chat thread' directly conveys the core purpose. It's appropriately sized for a simple tool and front-loaded with the essential action, making it easy to parse quickly.

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?

Given the tool's complexity (a mutation operation with no annotations and no output schema), the description is incomplete. It lacks behavioral context (e.g., what happens on success/failure), doesn't explain return values, and provides minimal guidance. While the schema covers parameters well, the overall context for safe and effective use is insufficient, especially for a write operation.

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 description adds no parameter-specific information beyond what's in the schema, which has 100% coverage with clear descriptions for thread_id, user_id, and message. Since schema_description_coverage is high, the baseline is 3 even without additional param details in the description. The description doesn't compensate but doesn't need to, as the schema adequately documents the parameters.

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 'Send a message in a chat thread' clearly states the action (send) and target resource (message in chat thread), making the purpose immediately understandable. It distinguishes from siblings like fc_list_chat_messages (list vs send) and fc_create_post (post vs chat message), though it doesn't explicitly name these distinctions. The description is specific enough to avoid being vague or tautological.

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., thread must exist), exclusions (e.g., not for bulk operations), or direct alternatives like fc_create_comment or fc_create_post for different contexts. Without such context, the agent must infer usage from the tool name and schema alone.

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