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

Annotations already declare the mutation profile (readOnlyHint=false, non-idempotent, open-world), and the description adds real value on top: it discloses the side effect (sends a magic link), the async follow-up step, the automatic MCP key delivery, and that no auth is required. It stops short of the return shape/rate details, but the flow disclosure is well beyond the annotations.

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?

Four tight sentences, front-loaded with the action, then the follow-up flow, then the anti-pattern warning. No filler; every sentence carries procedural 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?

For a three-parameter initiation tool with no output schema, the description supplies everything an agent needs: the action, the async continuation, the automatic key delivery, and the absence of auth. Nothing required to call 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%, so email, client, and locale are already documented in the schema. The description adds no parameter-specific meaning beyond the schema, which is the expected baseline when the schema does the heavy lifting.

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 and resource ('Start Compabase account setup for an email') and immediately characterizes the mechanism ('Sends a magic link'). It clearly separates this initiation step from the sibling tool it names, check_signup, so an agent can pick the right one 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 the full operating procedure: poll check_signup with the returned setup_id until status is ready, and explicitly instructs not to ask the user to generate a key in the portal. This is a textbook when-to-use plus named-alternative plus explicit exclusion.

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