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

Annotations already provide the safety profile (readOnlyHint, idempotentHint, non-destructive), so the description's added value is the rate limit and cost model: 10 free calls/day, then $0.001/call, with two payment paths (x402 _meta or X-API-Key). That is exactly the kind of operational context an agent needs before looping over addresses. It omits whether unknown or ambiguous addresses return an error versus a soft failure, but the output schema likely covers that.

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-loaded question establishes intent, followed by the supported-chain list, the benefit, and the pricing terms. The billing sentence and the '[served by tools.moneytools.dev]' tag are dense but each carries practical information; no filler prose.

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?

A one-parameter read-only validator with a full schema and an output schema needs little more: supported chains, cost limits, and payment mechanics are all present. The only real gap is failure semantics for malformed or multi-chain-ambiguous addresses, which the output schema presumably expresses.

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?

With a single parameter at 100% schema coverage, the baseline is 3; the description earns above baseline by spelling out which address encodings are accepted (checksum EVM, SegWit/Taproot, bech32 Cosmos, etc.), which tells the agent what the 'any crypto address' input realistically means. It does not discuss invalid-input handling.

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?

States a specific verb and resource in the opening question ('is it well-formed?') and enumerates exactly which address formats are covered (EVM checksum, Bitcoin legacy/P2SH/SegWit/Taproot, Litecoin, Dogecoin, Tron, Solana, Cosmos bech32, TON). That detail separates it from siblings like address_profile or chain_info, which imply lookup rather than format validation.

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?

'Catches typos before sending' gives a clear use context: validate immediately prior to a transfer. There is no explicit statement of when not to use it or a named alternative (e.g., address_profile) for richer data, so the guidance is clear but not exhaustive.

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