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

Annotations only flag destructiveHint=true, so the description correctly adds the non-obvious partial-update semantics and names the underlying endpoint (PUT /Leads with LEAD_ID), which helps interpret errors. It does not disclose the consequences of the destructive hint — e.g. that omitted fields survive but null clears values, or that this overwrites existing lead data — and it does not contradict the annotation.

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 purpose front-loaded and no filler. The endpoint sentence is the only one of debatable value, but it is compact and could aid error interpretation.

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?

A 25-parameter mutation tool with 40% schema coverage, no output schema, and minimal annotations needs considerably more description than three sentences. The agent gets no guidance on id sourcing, partial-update edge cases, or return behavior.

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 is expected to compensate and does not: it names only the implicit LEAD_ID identifier. Nothing is said about the relation id fields, custom_fields shape, or the meaning of ids such as lead_status_id beyond what the schema already states.

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 ('Update a lead'), which cleanly separates it from insightly_create_lead and insightly_update_contact. It does not, however, contrast itself with siblings like insightly_get_record to confirm an existing lead is being modified.

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?

'Only the fields you pass are changed' is a useful partial-update note that tells the agent it may send a sparse payload. Beyond that there is no when-to-use guidance: no mention of reading the lead first, of prerequisite ids, or of which sibling to use instead for creation or lookup.

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