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

With only destructiveHint=true in annotations, the description carries the behavioral burden well: it discloses de-duplication keys, Lead Flow routing, agent notification, action-plan execution for Registration/Inquiry, and the non-obvious 204 semantics (archived source → event silently ignored). It also warns that events older than a day are historical and skip workflows.

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 dense paragraph, front-loaded with the primary action and then layering behavioral caveats; every sentence carries distinct information. It is information-dense rather than padded, though the run-on structure makes the routing/notification clauses slightly harder to scan.

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-parameter, nested-object write tool with no output schema, the description covers the important behavioral and response semantics (de-dup, side effects, 204). It leaves out auth/permission requirements and what a successful non-204 response returns, which an agent would need for full error handling.

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; the description earns credit for adding cross-parameter meaning — that emails/phones drive de-duplication while person.id targets an existing contact, and that Inquiry types are auto-resolved to Property/General Inquiry. It does not add format guidance beyond what the schema already documents.

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 ('Add a new lead or record activity on an existing one') and explicitly frames it as 'FUB's documented way to create leads', which separates it from siblings like fub_update_person or fub_create_deal. The underlying endpoint (POST /v1/events) pins down exactly what is being invoked.

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 clear selection context: use it to create a lead, use person.id to target an existing contact, and note that FUB de-duplicates by email/phone. It stops short of naming an alternative for the adjacent case (e.g. modifying an existing person's fields via fub_update_person) or stating when not to send an event.

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