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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered. The description goes beyond that by supplying the status_id code legend (1 draft … 6 reversed), which is genuinely useful behavioral context for interpreting returned records given there is no output schema. It stops short of describing pagination defaults or result ordering, so not a 5.

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 tight sentences, each earning its place: purpose first, then the filterable dimensions, then the status-code legend and endpoint. The most decision-relevant information is front-loaded with 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?

For a nine-parameter, zero-required listing tool with no output schema and only a readOnly annotation, the description supplies the missing piece an agent needs to interpret results (status code meanings). It leaves minor gaps around pagination behavior and sorting defaults, which the schema partially covers.

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 all nine parameters are already documented; the baseline is 3. The description echoes the client and payment-status filtering (client_id, client_status) but adds no format or syntax detail beyond the schema, and its status_id legend refers to a returned field, not an input parameter.

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?

The description states a specific verb and resource ('List invoices') and immediately narrows the scope to client and payment-status filtering, which cleanly separates it from sibling get_invoice (single record) and from the other list_* tools keyed to different resources. An agent can identify the tool's role without opening the schema.

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 notes what the results can be filtered by, which hints at usage, but never says when to choose this over get_invoice or the other list tools, nor does it state any precondition or exclusion. Guidance is implied at best and absent in any comparative sense.

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