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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true), so the bar is lower, yet the description adds genuinely non-obvious behavior: patch semantics and the cross-tool side effect that booking inserts the vendor into the budget and a later quote updates that expense. It stops short of saying whether status transitions are validated or whether a rejected status without decision_reason errors out.

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 short sentences, front-loaded with the core action, then the patch rule, then the side effect. No filler and nothing redundant with the title.

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 15-parameter destructive mutation with no output schema, the description covers the hardest things an agent needs: partial-update semantics and the budget-side consequence of booking. Remaining gaps are the undocumented scalar fields and error/validation behavior on invalid status transitions, which keep it from being complete.

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 47%, just below the point where the schema carries the tool alone, so the description should compensate more. It adds real meaning for status (booking creates a budget expense, rejection requires decision_reason) and hints at quoted_amount/follow_up_on/contact fields, but most of the 15 parameters — name, notes, address, included, contact_name, decision_note — get no added explanation and remain undocumented in the schema too.

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?

Uses a specific verb-plus-resource opening ("Changes a vendor") and enumerates the field groups affected: status transitions, quote, follow-up date, contact details. It is clearly distinct from add-vendor/delete-vendor by the word 'Changes', though it never names a sibling explicitly.

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 line "Only the fields you pass change" is a useful signal that this is a partial/patch update rather than a full replace, which guides invocation style. However, there is no explicit when-to-use vs. alternatives guidance (e.g. use add-vendor to create, delete-vendor to remove) and no stated prerequisites or exclusions.

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