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

Annotations already establish read-only, idempotent, open-world, non-destructive, so the bar is lower, and the description clears it: it discloses the payment model ($0.02 per call over x402 on Base), the auth mechanism (prepaid x-credit-token header for unlimited calls), the absence of a free tier, and the upstream source (Sourcify). The only blemish is that 'No API key required' is stated twice, which reads as filler rather than added disclosure.

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?

Front-loads the core question and the data source, then sequences source, output shape, auth, and pricing in a logical order. It loses a point for the verbatim duplication of 'No API key required', which serves no purpose the second time.

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?

An output schema exists, so the return shape need not be spelled out, yet the description still summarizes it usefully. For a single-param read-only lookup it covers source, scope, cost, and auth; what is missing is what an agent should expect when a contract is unverified or only partially matched.

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?

One parameter at 100% schema coverage, so the schema already documents 'address' fully. The description only restates it as 'Required input: address' and adds the mild contextual constraint that it must be a Base contract; it adds no format, checksum, or validation detail beyond that. Baseline 3 for a fully-covered single param is correct.

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?

Specific verb and resource: checks Sourcify for a Base contract's verification status and returns its ABI as function/event name lists with an item count. It distinguishes itself by naming the data source (Sourcify), the chain (Base), and the match semantics (full or partial), but it never names the adjacent siblings (contract_info, contract_danger, proxy_check) it could be confused with.

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 rhetorical opener 'Is this Base contract verified?' hints at intent but is not a usage rule. There is no statement of when to pick this over contract_info, contract_danger, or proxy_check, and no exclusions or prerequisites for the call itself beyond the required address.

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