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

Annotations declare destructiveHint=true, so the safety profile is already flagged; the description adds genuine mitigating context by disclosing that unspecified fields are preserved (partial update), which softens the destructive reading. It still omits auth requirements, failure behavior for unknown ids, and whether changes are reversible.

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 no redundancy; the mutating-field list comes first and the patch caveat second. The trailing REST endpoint note ("PUT /Opportunities with OPPORTUNITY_ID") is borderline filler but does anchor the operation.

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 14-parameter mutation tool with no output schema, the description covers the essential shape but leaves gaps: no return-value expectation, no error/id-not-found behavior, and no guidance on the two owner-ish id fields. Adequate but not complete.

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 86%, so the baseline is 3 and the schema carries most parameter meaning. The description's field list loosely maps to bid_amount/probability/forecast_close_date/owner/details, but "owner" is ambiguous between owner_user_id and responsible_user_id, both of which lack schema 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 (Update) and resource (an opportunity), and enumerates the field categories affected (value, probability, dates, owner, details). This clearly separates it from insightly_create_opportunity by name, though the description itself never explicitly routes the agent away from siblings.

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" gives useful patch semantics for how to call it, but there is no explicit when-to-use guidance versus insightly_create_opportunity, no prerequisites, and no mention of required permissions or what happens on an invalid id.

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