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

Goes well past the annotations (readOnly=false, idempotent=true, destructive=false) by describing the full state machine: buyer accepts or disputes, hash enters the signed Invoice Passport, refused after acceptance, and Billify does not verify the work. It stops short of saying what a re-declaration does to the previously recorded hash/version, which matters given idempotentHint=true.

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?

Four short sentences, front-loaded with what is recorded, followed by lifecycle outcome, retry rule, and the trust disclaimer that prevents an agent from over-claiming verification. Nothing is redundant.

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 mutation tool with no output schema, the description covers lifecycle, refusal conditions, and trust boundaries well. The gap is the return/state effect of a declaration (what the agent gets back, what happens to a prior declaration), which an agent acting on the invoice would want.

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 only 25% (only content_hash is documented), so the description must compensate, and it does: it identifies 'a description' as the core content, 'a link' as the optional url, and 'a SHA-256 hash of the content' and ties the hash to the signed Invoice Passport. It does not say whether the link must be publicly reachable or whether a re-declare replaces the stored values.

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: 'Record what was delivered for an invoice', naming exactly the fields it captures, then explains the acceptance/dispute lifecycle. This clearly separates it from siblings like create_invoice, send_invoice, and get_invoice_passport.

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 conditions are given for both directions: re-declare only 'if the buyer disputed ... after fixing it', and the call is 'refused once the buyer has accepted'. An agent can decide whether to invoke it without opening the schema.

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