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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false): screening cadence (every 6 hours), the status transitions that trigger a webhook (clear/review/alerted), HMAC signing, that each call creates a new monitor (justifying non-idempotency), that ids/secrets are shown once, and the full payment model ($0.010 USDC via x402, PaymentRequired on unpaid, no charge on failure). This is exactly the extra context annotations cannot carry.

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?

Front-loaded with the purpose and behavior, then alternatives, then cost — a sensible order with no filler sentences. It is a long single block, but each clause carries distinct operational information, so length is justified by tool complexity rather than 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?

For a non-idempotent, billable, webhook-producing creation tool with a rich schema and an output schema present, the description covers everything an agent needs: cadence, trigger conditions, one-time secrets, mutation semantics, and payment failure handling. Nothing material is left to inference.

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 already 100%, so the baseline would be 3, but the description adds real meaning: it defines the wallet-vs-entity semantics of 'type', describes the webhook as an HMAC-signed public HTTPS endpoint, notes 'chain' is informational, and explains that 'label' is echoed in results and webhooks. It enriches rather than repeats the schema.

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?

States a specific verb+resource+scope ('Start 30 days of watchlist monitoring for one wallet address or one person/company name') and immediately disambiguates itself from siblings. An agent can distinguish it from screen_entity, screen_wallet and check_watchlist_monitors without opening any 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?

Explicitly routes the agent: 'Use it for ongoing monitoring after onboarding; use screen_entity or screen_wallet for a one-off check, check_watchlist_monitors to read statuses, and cancel_watchlist_monitor to stop.' Both the when and the alternatives are named with the condition that selects each.

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