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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals that this is a lookup and hints at a trial/signing requirement, but it does not explain what 'signed wallet' means operationally, how account age is expressed (days, blocks, seconds), or what error/rate-limit behavior to expect. This is minimal context for a safe read operation.

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 short and the core action is front-loaded, but the 'Account Age:' prefix redundantly repeats the tool name, and the emoji plus promotional trial sentence add marginal informational value. It is concise, yet not optimally structured since a sentence is partly occupied by marketing rather than useful guidance.

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?

This is a three-parameter lookup tool with no output schema and no annotations, so the description is the sole source of context. It omits essential calling details: what the return value represents, which parameters are actually required, supported chains, and how the 'signed wallet' requirement affects invocation. An agent cannot confidently call this tool correctly from the given definition alone.

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 per the rubric. The description itself adds nothing beyond the schema, and the schema's own parameter descriptions ('Chain to process', 'Wallet to process', 'Address to process') are tautological. The description does not clarify whether 'wallet' and 'address' are synonyms, alternatives, or both required.

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 specific verb ('lookup') and resource ('Blockchain account age'), which distinguishes it from general age tools like x402-age and x402-domain-age by scoping to blockchain accounts. However, the phrase 'account age' alone is still slightly ambiguous, and the description begins by repeating the tool name rather than clarifying scope further.

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 provides no guidance on when to use this tool versus alternatives, no prerequisites, and no exclusions. The only conditional phrase is the free-trial caveat ('per signed wallet'), which does not inform selection criteria. An agent must infer that 'Blockchain' is the differentiator from related siblings like x402-age and x402-domain-age rather than being told explicitly.

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