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

readOnlyHint=true already establishes the safety profile, so the description's burden is lighter. It adds 'Paginated' and the underlying REST endpoint (GET /invoices), which is useful for mapping, but says nothing about default page size, result ordering, or response shape beyond what the annotations and schema imply.

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 compact sentences, front-loaded with the core action and scope, then pagination and the API mapping. Nothing is redundant and nothing is padded.

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 an all-optional, fully documented list endpoint with a readOnly annotation and no output schema, the description covers action, filters, and pagination. It omits sorting behavior and any hint of result volume, which is a minor gap rather than a blocking one.

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 every parameter (to, from, page, per_page, state, client_id, project_id, updated_since) is already documented in the schema. The description's filter list mirrors those parameters without adding format or interaction detail, so the baseline of 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 ('List invoices') and enumerates the filter dimensions, which cleanly separates it from the sibling harvest_get_invoice (singular fetch). It never names an alternative tool explicitly, but the List/Get distinction is unambiguous.

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 phrase 'optionally filtered by...' implies the tool's usage context, but there is no guidance on when to prefer this over harvest_get_invoice or how the filters interact. Usage is inferable rather than stated.

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