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

Annotations declare destructiveHint:true and readOnlyHint:false, and the description aligns without contradiction. It adds valuable context beyond annotations: states that QuickBooks cannot delete a payment method, suggests using Active:false to retire, warns against sending sensitive fields, and explains sparse update semantics. This is meaningful behavioral disclosure.

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 reasonably concise given the complexity of update semantics. It front-loads the purpose and prerequisites, then covers important caveats. Every sentence adds meaningful information; no filler.

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?

Given the tool's complexity (sparse updates, full update behavior, deletion constraint, protected fields) and the absence of an output schema, the description covers the essential operational details an agent needs. It doesn't address return values, but that's acceptable without an output schema. The company parameter is simple and self-explanatory.

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 parameter's description in the schema already covers the required fields, sparse behavior, and constraints. The tool description adds no new parameter-level information beyond the schema, so the baseline of 3 is appropriate.

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 clearly states the verb (update), resource (existing payment method), and product (QuickBooks Online). It specifies required fields (Id and SyncToken), distinguishing it from create_payment_method and search_payment_methods by the 'existing' qualifier. No ambiguity.

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?

Provides explicit prerequisites: 'fetch the PaymentMethod first' and 'requires Id and SyncToken'. Explains the sparse vs. full update behavior and when to use sparse:false. Does not explicitly name alternative tools, but the context is clear that this is for modifying existing payment methods, not creating or searching.

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