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

Annotations only declare readOnlyHint=false, so the description carries most of the burden and delivers real behavioral value: outbound message content is filtered and contact details are stripped to keep deals on-platform. It still omits delivery/permission/state prerequisites, but the content-moderation disclosure is meaningful.

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?

Two sentences, zero filler, with the addressee and purpose front-loaded before the constraint. Nothing could be cut without losing information.

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?

An output schema exists, so return values need no explanation, and the schema covers all four parameters. The description covers purpose, recipient, and content restriction; only state/permission preconditions for sending 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?

Schema description coverage is 100% and every parameter (id, body, seller_id, buyer_token) is already documented there, so the baseline is 3. The description adds only a loose echo of 'contact details are removed' for body semantics.

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 names a specific verb+resource ('Message the other side of a task') and adds two concrete use cases (clarify the brief, ask questions). It is clearly distinguishable from list_messages and answer_clarifications, though it never names those siblings explicitly.

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 implies when to use the tool via parenthetical examples, but gives no explicit when-not guidance or alternatives (e.g. answer_clarifications vs. send_message, or when to reply vs. open a new thread). Usage is inferable rather than stated.

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