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

Annotations only declare destructiveHint=true, so the description carries the real burden and delivers: de-duplication by email/phone, Lead Flow routing, agent notification, action plans for Registration/Inquiry, and the meaning of a 204 response (archived source, event ignored). This is uncommon depth beyond structured fields.

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 sentences, zero filler, front-loaded with the create-vs-activity distinction and the response-code caveat last where it belongs.

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 10-param nested write tool with no output schema, the description covers the create/activity duality, de-dup behavior, side effects, and the key response outcome (204), leaving only auth/rate-limit details unstated.

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 coverage is 100%, so the baseline is 3, but the description adds non-obvious semantics: de-dup keyed on email/phone, person.id targeting an existing contact, and the type-driven side effects (Registration/Inquiry). It clarifies the two required params beyond their field-level descriptions.

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+resource pair ('Add a new lead or record activity on an existing one') and frames it as FUB's documented lead-creation path, mapping to POST /v1/events. An agent can distinguish it from fub_update_person or fub_add_note without opening the 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?

It gives conditional guidance inline ('use person.id to target a contact', de-dup by email/phone) but never states when to choose this over fub_update_person for modifying a contact, nor any exclusions. Usage is implied rather than stated.

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