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

With annotations already declaring readOnlyHint=false, idempotentHint=true, and destructiveHint=false, the safety profile is covered. The description adds valuable context beyond that: 'no money moves and no external contact is made' and 'the current pilot remains free,' which prevents an agent from assuming side effects the name implies. It also discloses the prerequisite state (verified counterexample + receipt acknowledgment) that must exist before calling.

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 dense sentences, each earning its place: purpose, call conditions, precondition, and exclusions. The most decision-relevant fact (what the tool records) is front-loaded, followed by when-to-call guidance. There is no filler, repetition, or redundant restating of schema content.

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 4-parameter tool with two const values, the description is nearly complete: purpose, invocation gating, preconditions, and behavioral exclusions are all present, and idempotency/destructiveness ride on annotations. The only notable gap is that nothing is said about the return value or how success is surfaced, which matters more because there is no output 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 description coverage is 50%, so the description compensates by giving meaning to the two constrained parameters: price_usd maps to 'priced at 29 USD' and voluntary maps to 'explicit, voluntary, nonbinding interest.' It also clarifies attempt_id's provenance via the verified-counterexample/receipt-acknowledgment precondition. The other two parameters are already documented in the schema, so the description need not repeat them.

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 opens with a specific verb and resource: 'Record explicit, voluntary, nonbinding interest in a future package priced at 29 USD.' It actively differentiates from siblings by warning 'never infer interest from generating or receiving a package,' which disambiguates it from generate_regression_examples and acknowledge_package_received. The clarification that this is 'not an order, checkout, subscription, purchase or payment' removes any ambiguity about the tool's role.

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?

The description gives explicit call conditions: 'Call only when the user or client has expressly indicated this interest,' plus an exclusion ('never infer interest from generating or receiving a package') and a hard precondition (verified counterexample plus explicit receipt acknowledgment). It also enumerates what the tool is not (order, checkout, subscription, purchase, payment), leaving no room for an agent to invoke it incorrectly.

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