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

With no annotations, the description carries the full behavioral burden. It does disclose genuinely useful lifecycle context ('Legacy', superseded by another tool), which is not in any structured field, but says nothing about side effects, required permissions, wallet handling, or what the mutation produces.

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, zero filler, with the deprecation status front-loaded before the alternative. Every clause earns its place.

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 annotations, no output schema, and 0% parameter coverage, the description does the deprecation job but not the invocation job. An agent still cannot tell which inputs are required, what the call returns, or what it costs.

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 0%, so the description must compensate and largely does not. 'More assets and networks' loosely gestures at the chain parameter, but product_id, chain, and buyer_wallet are left entirely undefined in both schema and description.

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?

Identifies the resource (USDC invoice endpoint) and clearly distinguishes it from the sibling create_crypto_invoice, so an agent can tell them apart without opening schemas. The creation verb is only implied via the name rather than stated, keeping it out of 5 territory.

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?

Explicitly routes new purchases to create_crypto_invoice and gives the reason (more assets and networks), which is actionable when-to-use guidance. It does not spell out the one scenario where this legacy tool should still be chosen, so it stops short of a full when/when-not pair.

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