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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavior beyond that: a concrete cost ($0.002 USDC per call via x402) and an extra detection scope (flags private keys and tx hashes pasted by mistake). It stops short of describing the return shape or failure behavior.

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 with the purpose and the pre-send-money intent, then a dense but useful chain enumeration, then cost. No filler sentences. The chain list is long but each entry conveys real supported coverage.

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 output schema, the description should ideally sketch what a result looks like (valid/invalid, checksum error, flagged-as-private-key). It says the tool 'checks' and 'flags' but never describes the return, leaving a gap for an agent that must interpret the result. Cost and safety are otherwise covered.

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 0% for the single 'address' parameter, so the description must carry the meaning. It partially compensates by enumerating the accepted formats and chains, telling the agent what kind of string to pass, but it does not state that the value is a single raw address string and gives no format constraints.

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 ('Check a crypto address') and enumerates the exact address families supported (EVM EIP-55, Bitcoin base58check/bech32, Solana, Tron), which lets an agent scope the tool precisely. It does not, however, differentiate itself from the sibling 'address_verify' or 'btc_address', so the agent cannot tell from the text which validate-vs-verify tool to pick.

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?

'before sending money' gives a clear implied usage moment for the tool. But there is no explicit when-not guidance and no mention of the obvious alternative 'address_verify', leaving the agent to guess between the two siblings on its own.

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