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

With no annotations to lean on, the description carries the full burden of behavioral disclosure. It does this well by explaining important side effects: inputRequired transitions the hire to input_required and extends the delivery window, and requester replies automatically resume the task to in_progress. It omits auth/error details but covers the core behavior.

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 long, front-loads the primary purpose, and contains no filler. Every sentence contributes behavioral information that belongs in the description.

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 moderate complexity, lack of annotations, and no output schema, the description covers the essential operational context: active-hire messaging, provider input-required behavior, and automatic resume. Minor gaps like return values and error handling are not critical for a straightforward send-message action.

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 the baseline is 3. The description adds meaningful context beyond the schema by explaining that inputRequired is provider-only and describing its state-transition and delivery-window effects, which the schema does not convey.

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 object: 'Send an A2A-style message,' and scopes it to 'within an active hire,' making the tool's function immediately clear. This also distinguishes it from the many other service_* sibling tools, such as service_hire_status or service_deliver.

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 clearly indicates when to use the tool: only within an active hire. It also explains role-based usage: providers can set inputRequired=true to pause and request clarification, while requester replies resume the task automatically. Although no explicit alternatives are named, the context is well-defined.

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