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

Annotations only cover readOnlyHint and openWorldHint, but the description discloses substantial extra behavior: pricing ($0.20 USDC via x402 on Base mainnet), the exact failure mode (unpaid call returns a PaymentRequired challenge) and the recovery path (retry identical call with signed payload in _meta["x402/payment"]). It also flags the output origin (DeepSeek-synthesised) and epistemic framing (ICD-203 estimative language), which is valuable for interpreting results.

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 core purpose is front-loaded in the first sentence, followed by parameter guidance, return contents, and critical payment semantics. The payment/retry instructions are necessary for correct invocation and earn their length, though the DeepSeek-synthesised/ICD-203 sentence is slightly more editorial than strictly required.

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?

With no output schema, the description carries the burden of describing return contents, and it does: matched ATT&CK ICS techniques mapped to D3FEND countermeasures with priority and rationale plus architecture recommendations. Combined with the payment flow and parameter combination rule, an agent has everything needed to call it successfully.

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 both the parameter meanings and the at-least-one-of constraint are already fully documented in the schema. The description restates the selection rule but adds no syntax, format, or ambiguity resolution beyond what the schema provides, so the baseline of 3 applies.

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 ('Prescriptive D3FEND-mapped mitigation guidance') plus scope ('for OT/ICS threats'), which distinguishes it from siblings like getComplianceMapping or getCveTriage. An agent can identify the deliverable (ATT&CK ICS techniques mapped to D3FEND countermeasures with priority and rationale) without opening the schema.

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 clear context (OT/ICS threats) and the parameter-combination rule ('Pass one of actor, cve_id, or technique_id, optionally with vendor_stack'), which is implied usage guidance. However, it names no alternative sibling tools and provides no when-not-to-use guidance, leaving routing entirely to inference.

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