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

No contradiction with annotations: readOnlyHint=false and destructiveHint=true align with an update operation. The description adds the prerequisite context that a current SyncToken is required, but it doesn't describe overwrite or clear semantics; the schema compensates and the destructive annotation already signals mutation. With annotations covering the core safety profile, this is adequate but not rich.

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?

One tightly scoped sentence that front-loads the action and resource and includes the essential precondition. No filler, with details correctly left to the schema.

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?

Together with the input schema's detailed entity semantics and the destructive annotation, the description provides a clear, callable picture: what the tool does, what must be passed, and the risk profile. No output schema exists, but return-value documentation is not required here. It could name the full workflow explicitly, but nothing critical 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%, and the schema's entity description already documents Id, SyncToken, sparse update behavior, and sensitive-field exclusions. The tool description only echoes the Id/SyncToken requirement and adds no new parameter meaning. 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 action ('Update'), the resource ('existing budget'), and the platform ('QuickBooks Online'), while the requirement for Id and SyncToken clarifies scope. This clearly distinguishes it from sibling create_budget and delete_budget operations.

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 phrase 'existing budget' implies the tool is for modifying an already-created record, not for creating or deleting one. The prerequisite of Id and SyncToken and the schema's instruction to fetch the Budget first give workflow guidance, but the description does not explicitly name alternatives or when-not-to-use conditions. Usage is implied rather than stated.

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