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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds genuine domain context a payment-named tool needs: it retrieves an accounting record of a vendor payment and does not initiate any bank or card movement.

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 verb+resource, then the routing condition, then the disambiguation caveat. 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?

With no output schema, the description still communicates that the return is a single accounting record for a vendor payment. It stops short of noting error behavior for an unknown Id or how company resolution failures surface, but it is sufficient to call the 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 coverage is 100%, so both parameters (id, company) are already documented in the schema. The description only echoes 'by Id' and says nothing about the multi-company selection semantics, so the 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 verb and resource ('Get a single bill payment from QuickBooks Online by Id') and distinguishes the entity from a bank/card payment, which is the main ambiguity for a payments-named tool. An agent can identify exactly what this retrieves.

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?

It gives a usage condition ('when no search or write answer already holds it'), implicitly routing the agent to search_bill_payments / create_bill_payment when those suffice, and excludes bank/card payment actions. It never names the sibling tool explicitly, so the routing is inferred rather than stated.

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