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

The annotations already disclose the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false). The description adds one genuinely useful fact beyond them: the required 'invoices:write' scope. It does not cover duplicate-invoice behavior, what happens on an existing invoice_number, or idempotency semantics for retries, which matters for a non-idempotent create.

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 short sentences, the purpose first and the authorization requirement second, with zero filler. Nothing could be removed 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 14-parameter mutation tool with no output schema, the description covers the auth requirement but says nothing about validation failures, uniqueness constraints, or the returned invoice identifier. Annotations carry the safety profile, but key create-time behaviors remain undocumented.

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% across all 14 parameters, with required fields and the status enum documented in the schema itself. The description adds no field-level meaning, 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?

The description states a specific verb and resource ('Create a new invoice'), which is unambiguous against get_invoice/update_invoice/delete_invoice. It does not distinguish itself from bulk_create, which is the nearest overlapping write tool, so it stops short of 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?

There is no guidance on when to use this versus bulk_create for multiple invoices, nor any note on prerequisites beyond the scope string. The agent must infer usage context entirely from the tool name.

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