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

With readOnlyHint=true already covering the safety profile, the description earns credit for disclosing the return envelope {count, results} and clarifying that count is the account total rather than the page length — a genuinely useful distinction an agent would otherwise misread. It does not cover auth or rate-limit behavior, but for a read-only list tool this is solid added context.

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 sentences, front-loaded with the resource and returned fields, followed by the return shape and endpoint. No filler and every clause carries 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?

There is no output schema, so the description correctly compensates by describing the return envelope and the meaning of count. Combined with 100% parameter documentation for this simple 2-param read tool, an agent has enough to call it correctly; only the paging-default nuance lives solely in the schema.

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 from/size are fully documented with pagination semantics in the schema itself. The description adds nothing about parameter units, defaults, or paging strategy, so the baseline 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 fields returned plus the endpoint (GET /v2/invoices). It does not explicitly distinguish itself from the sibling jobnimbus_get_invoice, but the list-vs-single-resource distinction is inferable from the name pairing.

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?

Usage is implied by the list semantics and the presence of jobnimbus_get_invoice as a sibling, but the description never states when to use this over get_invoice or how it relates to list_estimates/list_jobs. No exclusions or prerequisites are given.

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