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

Annotations only declare destructiveHint=true, leaving most behavioral burden to the description. The partial-update semantics ('only the fields you pass are changed') is a genuinely useful disclosure, but it omits permissions/scopes, whether omitted fields are preserved or nulled, and whether the operation is reversible. Not contradictory to the destructive hint, just incomplete.

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, front-loaded sentences with zero filler: purpose, mutation semantics, underlying endpoint. Nothing is padded or redundant.

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 25-parameter update tool with 40% schema coverage, no output schema, and only a destructiveHint annotation, the description is far too thin. An agent cannot tell which of the many fields are required beyond lead_id, how statuses/sources/owners are referenced, or what the response confirms.

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 only 40% across 25 parameters, so the description must compensate and largely does not. It never enumerates which fields are settable or clarifies the custom_fields null-clearing behavior, addressee IDs, or the difference between owner/responsible user id — all of which live only in the schema (or nowhere).

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 ('Update a lead') and adds the crucial partial-update rule ('Only the fields you pass are changed'). It does not explicitly contrast with siblings like insightly_create_lead or insightly_update_contact, so it stops short of 5.

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 implies mutation of an existing lead but gives no when-to-use guidance, no prerequisites, and no alternative routing (e.g., create_lead vs update_lead vs update_contact). Nothing tells an agent when this tool is the right choice.

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