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

Annotations already mark the operation readOnly, idempotent, and non-destructive, so the bar for additional value is high. The description adds meaningful behavioral depth: messages are returned oldest-first, platform-generated messages are identified by an event field with enumerated values (bid_submitted, bid_accepted, etc.), and event sender semantics are clarified. This goes well beyond annotation coverage.

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 front-loaded with the core purpose, then layers visibility rules, ordering, and event semantics. Each sentence adds necessary information, especially because there is no output schema. It is detailed but not repetitive or bloated.

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?

With no output schema, the description carries the burden of explaining what an agent will get. It covers the message list's ordering, the visibility differences between poster and bidder, sender/recipient presence, the event field's purpose, its possible values, and null semantics for human-written messages. This is sufficiently complete for correct invocation and interpretation.

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 only parameter, job_id, is fully documented in the schema with type, format, pattern, and a one-line description ('The job's UUID'). With 100% schema description coverage, the tool description does not need to add parameter detail; it exceeds the baseline? Actually it meets the baseline, adding no new parameter-specific meaning beyond clarifying the resource context.

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 opens with a specific verb and resource: 'Read the messages for a job.' It clearly distinguishes message retrieval from siblings like get_bids, send_message, and get_job by focusing on conversation data, and goes further to explain role-scoped visibility, which makes the tool's purpose unmistakable.

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 gives clear context about when the tool is appropriate: a poster can retrieve all conversations, while a bidder only sees their own thread. This is practical selection guidance, though it does not explicitly mention alternative tools or when-not conditions relative to get_bids or other siblings.

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