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

Goes well past annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true) by disclosing domain behavior: partial payments allowed, multiple payments per invoice, and the invoice state transition from Active to Paid once fully paid. It also names the authentication prerequisite (Cotlet API key with access to this app) and the per-call confirmation default, none of which the annotations convey.

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?

Front-loaded with the key scoping fact, but the paid transition is stated twice ('a fully paid invoice moves to Paid' and 'Once the invoice is paid in full it moves from Active to Paid'), and 'as Record Payment does in Joist' restates the name. Removing those redundancies would tighten it without losing information.

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 4-parameter mutation with no output schema, it covers prerequisites, confirmation policy, partial-payment semantics, and state effects. The only gap is that it never hints at what the call returns (e.g. the created payment or updated invoice), which matters slightly since no output schema exists to carry that.

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%, so amount format, the method enum, paid_on default, and invoice_id provenance are already documented in the schema. The description adds no parameter-level detail beyond that, so the baseline 3 applies rather than a higher score.

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 ('Record a payment on an invoice') and immediately delimits scope: payments received OUTSIDE Joist Payments, since Joist records its own payments. That distinction is a genuine differentiator in a large sibling set (dozens of *_record_payment tools plus Joist's own list/get invoice tools).

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?

Explicitly says when to use it (manual/off-platform payments) and when not to (payments taken through Joist Payments are recorded by Joist itself). It also sets the confirmation contract: confirm each call by default, switchable off, and mandatory user confirmation because it reaches other people.

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