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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. Beyond that, the description adds valuable behavior context by disclosing the exact return types (ALLOW/HOLD/BLOCK) and that a reason accompanies the verdict. It also explains the meaning of each verdict. No contradiction with annotations.

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 two sentences, front-loaded with the primary action, then the usage timing, then the verdict definitions. Every sentence earns its place with no redundancy or padding.

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 tool has 9 parameters and no output schema, so the description partially substitutes an output contract by explaining the three verdicts and their implications. It handles the core decision flow (ALLOW/HOLD/BLOCK), but does not mention error conditions (e.g., missing policy, invalid agent_id) or additional response fields like the 'reason' structure. For a pre-flight check tool, this is reasonably complete but not exhaustive.

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 100%, so the baseline is 3. The description does not add specific parameter-level meaning beyond what the schema provides; it only loosely references the 'proposed payment' and 'agent', which map to the required params (amount_usd, agent_id). It does not compensate with additional parameter context, but the schema fully covers each parameter.

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 uses a specific verb 'Check' and clearly identifies the resource: 'a proposed payment against the agent's active policy before executing it.' It also distinguishes itself from sibling tools like policy.create and settlement.execute by positioning this as a pre-execution gate, and the return values (ALLOW/HOLD/BLOCK) reinforce the unique purpose.

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 an explicit when-to-use instruction: 'Run this before every settlement call.' It also defines the next actions for each outcome (ALLOW = proceed, HOLD = route to human review queue, BLOCK = halt, do not proceed), giving the agent clear operational guidance on how to integrate this tool into a workflow.

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