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

Annotations already declare destructiveHint=true, so the mutation risk is covered. The description adds value beyond that: partial-update semantics (unpassed fields untouched) and the deliberate exclusion of state changes, which is important behavioural context an agent would otherwise guess at. Auth/permission and reversibility details remain unstated.

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, zero filler, and the primary action and partial-update rule are front-loaded before the exclusions and endpoint. Every sentence carries information an agent needs.

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 22-parameter mutation with no output schema, the description covers the essentials: scope, partial-update behaviour, and excluded operations. It could say more about permissions or failure modes, but nothing critical to calling it correctly is missing.

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% across 22 parameters, so the schema already documents each field with its own description. The description's field-family summary ('subject, customer, venue, dates, reference, instructions, tags, custom fields') is a useful grouping but adds no semantics beyond what the schema provides, so the baseline 3 applies.

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 header fields on an existing opportunity') and enumerates the field families affected. It also explicitly carves out what the tool is not (state transitions like convert/cancel/mark lost), which separates it from the create and get 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?

Gives clear usage context: 'Only the fields you pass are sent' tells the agent this is a partial update, and it explicitly excludes state changes. It stops short of naming which sibling to use for those excluded operations, so it is not a full when/when-not/alternative statement.

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