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

Beyond the destructiveHint=true annotation, the description discloses a genuinely behavioral fact: Insightly's server marks lead_status_id and lead_source_id required even though the local schema only lists last_name. That is non-obvious API semantics the schema does not carry. It still omits auth requirements and side-effect/error behavior.

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 tight sentences with no filler, front-loading the required field and then the hidden-required-field caveat. The trailing 'Insightly: POST /Leads.' is slightly redundant but harmless.

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 24-parameter create tool with no output schema, the description covers the critical creation-time gotchas but says nothing about what the call returns (a created lead record/id), failure modes, or whether omitted optional fields are defaulted. Adequate, but leaves real gaps.

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 low (38%) across 24 params, but the description compensates on the highest-risk gap by declaring last_name required and warning that lead_status_id / lead_source_id are required server-side, with pointers to the id-list tools. It does not add syntax or formatting detail for the remaining fields.

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 (Create) plus resource (lead), and is unambiguous against the create_contact / create_opportunity / create_organisation siblings. An agent knows exactly which entity is being created 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?

The description routes the agent to prerequisite lookups (insightly_list_lead_statuses / insightly_list_lead_sources) for valid ids, which is concrete when-to-use guidance. It stops short of contrasting with insightly_update_lead or insightly_create_contact, so it lacks explicit exclusions.

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