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

Annotations already declare the write/non-destructive/non-idempotent profile, so the bar is lower. The description still adds real context: the ledger has no payment or messaging channel (scope boundary) and that the call returns the ledger's invoices. It does not mention duplicate-entry risk despite idempotentHint=false, which is the one notable omission.

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, zero waste, and the usage trigger is front-loaded before the return note and the exclusions. Nothing is repeated from the title or schema.

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?

With annotations covering the safety profile, an output schema covering returns, and 86% schema description coverage, the description only needs to establish purpose, trigger and scope boundary — all of which it does. Nothing an agent needs to call this correctly is missing.

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 86%, so the schema already documents all seven parameters including kind, currency defaults and date format. The description only echoes vendor, amount, due date and the optional paid flag, adding no syntax or format detail beyond the schema — the baseline 3 for high coverage 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?

Specific verb+resource ('record an invoice, bill or receipt in their Xenition ledger') with the key fields named (vendor, amount, due date, paid state). It is clearly distinguishable from ledger siblings such as query_ledger and mark_paid, which the 'do not use to pay' clause implicitly separates it from.

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?

Explicit trigger ('use this when the user wants to record an invoice...') plus explicit exclusions ('Do not use to pay, send or email an invoice'). It stops short of naming the alternative tool (mark_paid) that should be used instead, leaving that routing to inference.

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