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

The description goes well beyond the existing destructiveHint annotation by explaining sparse updates, line-array replacement, full-update behavior, restricted field categories, and the Active:false retirement pattern. This gives the agent a strong understanding of the operation's side effects.

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 main description is a single, focused sentence, and the parameter schema contains detailed but well-organized guidance. Minor redundancy exists between the main description's 'requires Id and SyncToken' and the schema's 'Must include Id and the current SyncToken', but overall the definition is efficiently structured.

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 definition covers prerequisites, restricted fields, sparse vs. full update semantics, line replacement, the vendor-deletion limitation, and company selection. Given the rich schema and annotations, the lack of an output schema does not represent a meaningful gap for calling this tool correctly.

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 schema already provides detailed guidance for both entity and company parameters. The main description only restates the Id and SyncToken requirement, which is already in the schema, so it adds no new parameter-level meaning.

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 action ('Update an existing vendor') and the target system ('QuickBooks Online'), with a concise prerequisite. This distinguishes it from create_vendor, search_vendors, and vendor-credit tools in the sibling list.

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 and entity schema explain that Id and SyncToken are required, instruct the agent to fetch the Vendor first, and describe how to effectively retire a vendor since deletion is not possible. It provides clear context for when to use this tool, though it does not explicitly contrast it with create_vendor or other alternatives.

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