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

Annotations only declare destructiveHint=true, so the description carries most of the behavioral burden. It usefully discloses the underlying endpoint and the `extra` merge escape hatch, but says nothing about side effects, authentication/permission needs, duplicate-email handling, or what happens to unspecified fields. With annotations present the bar is lower, but the added context is thin.

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?

Three short sentences with the action front-loaded, followed by the parameter hint and the endpoint note. Nothing is redundant or padded, though the endpoint detail is the least essential element.

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 6-parameter, all-optional mutation tool with nested objects and no output schema, the description covers the accepted field set and the arbitrary-field escape hatch. However, with no output schema it never says what the response contains (e.g. the new contact id), and it omits mutation side effects, leaving a real gap.

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 all six parameters (given_name, family_name, email_addresses, phone_numbers, company_id, extra) are already documented in the schema. The description merely enumerates them and adds no format, slot, or shape detail beyond what the schema provides, so the baseline of 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?

The description states a specific verb and resource ('CREATE a new contact in the Keap CRM') and even names the underlying API call ('POST /contacts'), so the agent knows exactly what the tool does. It does not explicitly contrast itself with the create/update/get siblings, but the verb 'create' is unambiguous against keap_get_contact or keap_update_contact.

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 guidance on when to use this tool versus alternatives, nor any prerequisites (e.g. required fields Keap enforces, duplicate-handling behavior, whether an existing contact should be updated instead via keap_update_contact). The sentence about which fields to provide is parameter documentation, not usage guidance.

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