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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds one genuinely new fact not present in structured data: the call is FREE. It does not disclose what the response actually contains, which matters for a discovery tool with no output schema.

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 with no filler, and the resource is stated before the secondary purpose. Slightly terse for the ambiguity it leaves, but nothing is wasted.

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 no parameters and no output schema, the description carries the burden of explaining what the agent gets back, and it only gestures at 'where to inspect fresh payment requirements'. For an entry-point tool that other calls depend on, that leaves a meaningful gap.

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?

The tool takes zero parameters, which is the baseline-4 case; there is no parameter meaning for the description to compensate for.

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 verb 'Find' plus the resource 'x402 Gateway contract' gives a concrete target, and the second clause indicates it also surfaces where payment requirements live. However, 'where to inspect fresh payment requirements' is vague about the actual output, and nothing distinguishes it from the sibling x402_contract, which plausibly does something similar.

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?

No when-to-use guidance is given and neither sibling (sml_status, x402_contract) is named or differentiated. An agent must infer that this is an entry-point/discovery call rather than a contract-query call.

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