Post Dialogue Message

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

Annotations indicate a write operation (readOnlyHint=false) but no destructive or idempotent hints. The description adds valuable behavior context: messages are 'appended to the thread's history and are immediately visible to the other instance,' clarifying the non-destructive, atomic-like nature. It also states the return value (created message object with ID and timestamp), though it does not address failure modes or prerequisites.

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 appropriately sized with a clear structure: a one-sentence summary, a short contextual paragraph, a bulleted Args list, and a Returns note. Every element adds value, although the Args list partially duplicates the schema descriptions; the added semantics justify the length. It is front-loaded with the core purpose.

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 has 5 parameters, no output schema, and is the core communication primitive, the description is complete. It explains the purpose, role semantics, message behavior (append/visibility), and return value. It also covers optional metadata and the required parameters. No critical information is missing for an agent to invoke it correctly.

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 coverage is 100%, so baseline is 3. The description adds extra meaning by explaining that role identifies which instance speaks, content is flexible ('prose, code, structured notes'), and metadata is a JSON string for structured data. This goes beyond the basic property descriptions in the schema, providing context for each parameter's intended use.

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 tool's function: 'Post a message to a dialogue thread as either claude_app or claude_code.' It uses a specific verb and resource, and distinguishes itself from siblings by positioning itself as 'the core communication primitive' among read/manage/search tools.

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: it is the core communication primitive, implying it is the primary way to send messages in the dialogue system. It also explains how the role parameter determines which instance posts. However, it does not explicitly mention when not to use it or list alternative tools for specific situations.

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