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

Annotations already mark the tool as read-only, idempotent, and non-destructive; the description adds that the server never needs the key, that the output is signing material rather than an executed action, and that the environment is mock/test-only. This provides meaningful behavioral context beyond the annotation flags.

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 dense but efficient: each sentence earns its place by covering the return value, the signing workflow, the optional EIP-712 data, and the test-money caveat. No filler or redundant restatement.

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?

There is no output schema, so the description must explain return values; it specifies the exact JCS JSON structure, the header template, and the optional EIP-712 output. Combined with the workflow hint and safety caveat, an agent has sufficient context to invoke and consume the result correctly.

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%, so baseline is 3, but the description adds semantic relationships: it explains that body is represented as body_sha256 in the canonical payload and that contract_job_id plus contract_hash jointly enable the optional EIP-712 output. These insights go beyond the per-field schema descriptions.

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 states a specific verb and resource: it returns the canonical EIP-191 message and header template for an AFG API call, and optionally EIP-712 typed data. This clearly distinguishes it from siblings like afg_sign_contract (signs a contract) and afg_post_job (submits the actual request).

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?

It clearly describes the BYO-wallet workflow: sign locally, then pass signed_request={headers, body} to the matching tool. It gives strong usage context and a test-only warning, but does not explicitly name alternatives or state when not to use this tool.

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