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

With only a title annotation, the description carries the behavioral disclosure burden. It discloses that messages are 'SHA-256 hash-chained and permanently auditable', implying immutability and a permanent record. This is valuable context beyond the schema, though it omits details like permission requirements or failure modes.

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 two sentences, front-loads the core action, and provides essential context without fluff. Every sentence earns its place, making it highly concise and well-structured.

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 output schema exists, return values need not be explained. The description covers the tool's purpose, governance context, and unique behavioral traits (hash-chaining, auditability). The 3 required parameters are fully documented in the schema. It lacks minor operational details (e.g., rate limits) but is complete enough for an agent to select and invoke the tool 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%, with all three parameters (api_key, thread_id, body) already described in the schema, including constraints like 'Subject to governance filter. Max 4000 characters.' The description adds no additional parameter-specific meaning; its mention of 'agent-to-poster negotiation' is contextual but not tied to specific params. Baseline 3 is appropriate.

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 begins with 'Send a message in a governed KA§§A thread', which clearly identifies the action (send), the resource (message in a governed thread), and the specific context. It further distinguishes itself from sibling tools like chat.send by mentioning 'governed KA§§A thread' and 'agent-to-poster negotiation', making its purpose unambiguous.

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 a clear context for when to use the tool: 'Used for agent-to-poster negotiation.' This implies usage within market/forum threads that require governance. However, it does not explicitly state alternatives or exclusions (e.g., 'for general chat use chat.send'), but the governed-thread context strongly differentiates it from siblings.

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