wallet_from_mnemonic

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

Beyond the readOnlyHint annotation, the description adds valuable behavioral context: it does NOT return the private key, and it requires a specific environment variable because the mnemonic is agent-visible. This meaningfully clarifies security-sensitive behavior and complements the annotation without contradicting it.

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?

Three tightly written sentences deliver the core purpose, a critical limitation, and security gating. The description is front-loaded and contains no filler or redundant information.

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?

The description covers purpose, limitations, and gating, which is strong given the readOnly annotation and simple parameter set. However, it does not specify the returned address format or the target chain/coin type, and there is no output schema to fill that gap, so a small amount of ambiguity remains.

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?

The input schema already fully documents all parameters with names, types, defaults, and descriptions (100% coverage). The description only reiterates that account/address index are optional, adding no new semantic detail beyond the schema.

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 clearly states a specific action: 'Derive an address from a BIP-39 mnemonic at optional account/address index.' It also scopes the behavior by noting it does not return the private key and explicitly calls out the gating requirement, which helps distinguish it from related wallet tools.

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 practical guidance: it requires WEB3AGENT_ALLOW_AGENT_VISIBLE_SECRETS=1 and advises 'Prefer local CLI.' While it doesn't name a specific alternative tool, the preference for local CLI and the explicit gating condition provide clear context for when this tool should be used.

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