hey_screen

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

Annotations declare destructive/idempotent/openWorld, and the description adds substantial non-redundant context: reject does NOT mark spam, existing emails are untouched, the operation falls back to the contact-page clearance route, and it is reversible in the Hey UI but not via MCP. It even discloses the return shape, which annotations cannot.

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?

Front-loads the verb pair, then layers approve/reject semantics economically in a few tight sentences. Slightly heavy on parenthetical implementation detail (the /contacts/{id}/clearance path), but nearly every clause earns its place.

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 3-param mutation with no output schema, the description covers action semantics, edge cases (already-approved senders), side effects, reversibility, and return shape. Nothing the agent needs to invoke it correctly is missing.

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 the schema already documents destination defaults and that it is ignored on reject; the description largely restates these. It adds the 'screen out' alias and the approve routing/default, but no syntax or format detail beyond the schema, so baseline 3 applies.

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?

States a specific verb pair and resource ('Approve or reject a sender by email address') and explicitly differentiates from siblings by naming hey_list_screener and hey_screen_by_id. An agent can pick this tool over those without opening a schema.

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?

Gives explicit when-to-use routing ('Use hey_list_screener to see pending senders, or hey_screen_by_id for clearance IDs') and clarifies that reject applies to both pending and already-approved senders. The alternative tools and the condition selecting them are stated outright.

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