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

Annotations already signal a non-read-only, destructive operation, so the description does not need to establish that. It adds the useful context that updates target an existing estimate and require Id/SyncToken, but does not disclose the sparse-update or line-replacement behavior; that detail lives in the schema rather than the description.

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?

The description is a single front-loaded sentence with no filler words. It states the action, the target, and the key prerequisite clearly.

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?

The nested entity schema carries the substantive update semantics, and annotations cover the safety profile. The description is complete enough for an agent that reads the schema, though it would be marginally stronger if it called out the sparse-update behavior or explicitly routed to create_estimate for new estimates.

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 100%, and the entity property description already explains Id/SyncToken requirements, sensitive field restrictions, sparse versus full updates, and line replacement behavior. The description's mention of Id and SyncToken is accurate but redundant with the schema, so the baseline score of 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?

The description uses a specific verb ('Update') and resource ('an existing estimate in QuickBooks Online'), and the word 'existing' plus 'requires Id and SyncToken' distinguishes it from create_estimate and delete_estimate. An agent can tell this targets a previously created estimate without opening sibling schemas.

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 clearly implies this tool is for modifying an existing estimate and establishes the Id/SyncToken prerequisite, implying the estimate should be fetched first. It does not explicitly state 'use create_estimate for new estimates,' but the context is clear enough.

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