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

No annotations are provided, so the description carries the full behavioral burden. It discloses that the tool follows redirects, which is useful, but says nothing about redirect limits, timeout behavior, required permissions, rate limits, or what happens on failure. For a network-dependent tool with no annotation coverage, this is a significant gap.

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?

The description is a single sentence and appropriately sized for a simple URL expansion tool. However, the leading 'x402-url-expand:' duplicates the tool name and delays the actual purpose, which slightly reduces front-loading and efficiency.

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?

There is no output schema and no annotations, so the description should compensate by explaining what the tool returns and any key behavioral constraints. It does not describe the return value (e.g., final expanded URL) or clarify the ambiguous two-parameter schema. Given the tool performs a network operation, the description is incomplete for reliable invocation.

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 100%, so the baseline is 3 even though the description adds no parameter-specific meaning. The schema descriptions themselves are vague ('Url to process', 'Short to process'), and the description does not clarify how 'url' and 'short' differ or which to use. The high schema coverage keeps this at the baseline rather than lower.

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 states a clear verb and resource: 'Follow redirects to expand shortened URLs.' It is specific about the action, but it does not differentiate from siblings such as x402-url-unshorten or x402-redirect-trace. The redundant 'x402-url-expand:' prefix also restates the tool name without adding clarity.

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 no indication of when to use this tool versus alternatives like x402-url-unshorten or x402-redirect-trace. It also omits any prerequisites, such as network access or error handling expectations. The agent is left to infer usage from the purpose alone.

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