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

Annotations already declare readOnlyHint/openWorldHint/non-destructive, so the safety profile is covered. The description adds useful behavioral context beyond that: the default status scope (approved), the derived field rule (amount due = total - amount paid), and the Cotlet API key requirement. It adds genuine value but doesn't mention pagination or ordering.

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 opening two sentences are near-identical restatements of the same field list ('Tradify: Invoices with customer, job...' then 'Lists invoices with customer, job...'), which wastes space. The remaining sentences are tighter and front-load the default-status behavior, but the duplication costs it.

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 read-only list tool with a fully documented 3-param schema and no output schema, the description covers default behavior, status semantics, the derived amount-due field, and auth needs. That is sufficient to call it correctly; only minor details like pagination/ordering are absent.

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 all three parameters are already documented in the schema (including the enum values and defaults). The description reinforces the status default and adds a use-case for 'overdue', but adds little on limit or customer_id. Baseline 3 is correct when the schema does the documentation work.

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+resource ('Lists invoices') and enumerates the fields returned (customer, job, due date, total, amount paid, amount due). It is unambiguous what the tool does. It does not explicitly differentiate from Tradify siblings like list_quotes or list_jobs, which keeps it at a 4 rather than a 5.

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?

Gives real conditional guidance: 'By default it returns approved invoices; use status overdue to chase late payers.' This tells the agent when to reach for a specific status filter. No comparison to alternative sibling tools, so it stops short of a 5.

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