Reply to a buyer

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

Annotations already mark destructiveHint=true and readOnlyHint=false, but the description adds critical context: 'this cannot be unsent' and 'never send a test message.' This goes beyond the structured annotations to explain real-world consequences, making the tool's irreversible nature explicit.

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, front-loaded with the core purpose, followed by essential safety instructions. Every clause earns its place; no filler or redundant phrasing.

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 simple send-message tool with no output schema, the description covers the action, the irreversible nature, the confirmation requirement, and the prohibition on test messages. It is fully sufficient for an agent to use this tool safely and 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 description coverage is 75%, so the schema already documents text, confirm, and country. The description reinforces the confirm requirement ('Requires confirm: true', 'get their approval first') but does not add new semantic detail beyond what the schema's property descriptions already state, particularly for confirm. No significant parameter insight is added.

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 starts with 'Sends a message to a real person in a Vinted conversation' — a specific verb and resource that clearly distinguishes it from read-only siblings like read_messages and conversations. The 'real person' qualifier adds important context that this is a human-facing, non-test action.

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?

Explicitly states the required confirm:true workflow, instructs the agent to get user approval before sending, and warns that messages cannot be unsent. This provides clear when-to-use and guardrail guidance, effectively excluding casual or test usage.

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