Sign Message (BRC-100)

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

Annotations already include readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds valuable behavioral context beyond these: 'The private key never leaves the server' (security guarantee) and 'Requires an initialized wallet' (precondition). These details materially help the agent reason about invocation, so the description earns credit beyond the annotation baseline.

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 well-structured and front-loaded with the core purpose, followed by use cases, a security note, a prerequisite, and a compact Args/Returns listing. Every sentence contributes meaningful information without redundancy or fluff. It is concise yet complete for a single-parameter tool.

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?

For a tool with one parameter and no output schema, the description provides an unusually complete picture: purpose, use cases, security guarantee, prerequisites, parameter meaning, and return shape. The agent knows exactly what to expect and how to use it, and the description also contextualizes the tool among many wallet-related siblings. No significant gaps remain.

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 coverage is 100%, and the schema's property description ('Message to sign with the wallet key') already conveys the semantic meaning. The description's 'Args: - message (string): the message to sign' essentially restates the schema without adding new information about format, encoding, or constraints. Per the rubric, baseline 3 is appropriate when the schema does the heavy lifting.

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 opens with 'Sign an arbitrary message with the wallet's private key,' which is a specific verb+resource statement. The addition of the protocol identifier '(BRC-100 createSignature)' further pins down the exact operation. It is clearly distinguished from sibling tools like ordnet_verify_message by the explicit 'sign' action.

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 explicit use cases: 'prove control of the identity key, authenticate to a service, or sign an x402 payment authorization off-chain.' It also states a prerequisite ('Requires an initialized wallet'), which helps the agent know when the tool is applicable. It does not include explicit 'when not to use' or alternative tool suggestions, but the use-case list is sufficiently contextual.

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