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

Annotations only declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, which conveys that it is a local mutation but nothing more. The description does not say whether this overwrites an existing selection, whether the contact must already exist, or what authorization is required for a non-read-only write operation.

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?

A single efficient sentence with the verb front-loaded and zero filler. Its brevity is a virtue structurally, though it comes at the cost of the missing behavioral detail noted elsewhere.

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?

This is a mutation tool with no output schema and five completely undocumented parameters, so the description should do much more work. As written, an agent lacks the information to call it correctly beyond guessing parameter roles from names.

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 0% across 5 required parameters, so the description must carry the burden and it barely does. Only 'email' and the prospect concept are implied; projectId, siteId, prospectId, and idempotencyKey are entirely unexplained.

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 states a specific verb ('Set') and resource ('which email address outreach to a prospect goes to'), making the operation understandable. It does not explicitly differentiate itself from the nearby sibling find_prospect_contact, so the agent must infer the read-vs-select distinction from the names alone.

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?

There is no when-to-use or when-not-to-use guidance and no mention of alternatives such as find_prospect_contact. The agent gets a purpose statement but no context for choosing this tool over sibling contact/prospect tools.

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