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

Beyond the annotations, the description discloses that delivery happens by email or API (an external relay, reinforcing openWorldHint) and that the thread is persisted. This adds useful delivery/thread-persistence context. It does not cover permissions or reversibility, so it stops short of a 5.

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?

A single dense sentence is front-loaded with the core action and routing logic, and every clause (token roles, content kinds, attachments, relay mechanism, thread) carries information. It is efficient, though the packing makes it slightly harder to scan.

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 mutation tool with no output schema and six parameters, the description covers direction, intent, attachments, delivery channel, and thread persistence — enough to call it correctly. Only authorization/prerequisite detail and full enum coverage are absent.

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?

With only 33% schema description coverage, the description must compensate and does partially: it explains token role semantics (buyer vs supplier), optional file_ids, and content kinds. However it omits the 'note' enum value present in the schema and says nothing about rfq_id or body, leaving gaps.

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+resource (write/send a message about an RFQ) and clarifies the dual routing model — to matched factories via a buyer token versus to the buyer via a supplier token. This distinguishes it from the generic send_message sibling by anchoring the action to an RFQ thread.

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?

It gives clear context for which token/direction to use (buyer vs supplier) and enumerates the content intents (question/answer/update). It does not, however, contrast this tool with the sibling send_message or get_rfq_thread, leaving the agent to infer which of the overlapping messaging tools to pick.

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