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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description goes beyond them by explaining the actual effect: the executing broker checks every order or withdrawal and cancels pending execution on halt. It also discloses that halt carries no payment requirement and that the registrar timestamps versions, which is real operational context not derivable from the structured fields.

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 critical constraint ('emergency brake immediately') is front-loaded and the sentences are individually short. Some content — treasury caps, registrar timestamps, and the marketing page URL — is peripheral to invoking this specific tool, adding mild noise.

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 destructive, no-output-schema mutation, the description covers the effect and the payment posture well. It is still silent on the return value, on how approval/threshold rules affect a halt call, and on the role of wallet_signature, leaving gaps an agent would hit at call time.

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% and the schema itself gives no prose for mandate_id, action, or wallet_signature. The description partially compensates by pointing to /api/mandate-contract for 'integer units, signing formats, approval requirements', which maps to the signed/unsigned action union, but it never explains what wallet_signature is for or how the two action variants differ.

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 names a specific action (the 'emergency brake' that halts a trading mandate) and the endpoint POST /api/mandate-halt, so an agent can identify it as the halt operation rather than issue/amend/revoke. The framing 'Record the principal, broker or agent emergency brake' is slightly indirect, but the tool name plus endpoint make the purpose unambiguous.

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?

'Immediately' signals urgency and implies this is the emergency-stop path, which is meaningful guidance. However, it never explicitly contrasts halt with the sibling wever_mandate-revoke (permanent) or wever_mandate-status, so the agent must infer which of the mandate tools to pick.

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