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

Annotations only indicate non-destructive and non-open-world behavior, so the description carries the burden of disclosing mutation. It does this well by stating the tool 'writes' and records only, and by clarifying that no money movement occurs. It doesn't address idempotency or validation, but the essential side-effect profile is clear.

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?

Two short sentences that front-load the primary action and then state the key boundary. There is no filler, no repetition of schema information, and every clause earns its place.

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 description is adequate for a simple create operation with an output schema, and the required fields are present in the input schema. However, the vendorBill object has many optional fields with minimal schema descriptions, and the description offers no guidance on status, amounts, or date semantics, leaving some ambiguity for correct invocation.

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 0%, and the description adds no field-level meaning beyond the general concept of a bill owed to a vendor. With a nested vendorBill object containing many optional fields like status, paidAt, dueDate, and amountCents, the agent gets little help from the description in populating these fields correctly.

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 ('Records a bill') and resource ('the company owes a vendor'), and explicitly distinguishes the tool from payment operations by saying it 'does not pay anything or move money.' This clearly separates it from sibling tools like vendor_bill_mark_vendor_bill_paid.

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 gives clear context for when to use the tool: when recording an owed bill. It also provides an explicit exclusion, noting that marking the bill paid is a separate call, which prevents a common misuse. It doesn't enumerate all sibling alternatives such as cancel/get, but the key routing decision is covered.

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