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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description goes well beyond by disclosing the full x402 payment flow: call without payment_header first to get the challenge, sign with your own wallet, retry with the same business args, and that the server never holds a wallet. That is non-obvious operational context an agent cannot get from 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?

Front-loads the PAID tag and core purpose well, but the price ('$0.06 USDC on Base') is stated twice and the payment mechanics are repeated in both the description and the payment_header schema field, adding redundancy.

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 names the returned fields (dates, headlines, judgments, vs_prior, ranks), and it fully documents the payment handshake. Nothing an agent needs to invoke this paid tool correctly is missing.

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 the baseline is 3, but the description adds the mutual-exclusivity rule for topic vs id that an agent must honor. It does not add format examples beyond the schema, keeping it at 4 rather than 5.

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 ('trace') and resource ('ONE topic or ONE signal id across every dated archive brief'), and explicitly distinguishes itself from buying full history, which separates it from sibling signal_history. An agent can tell it apart 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?

Gives a clear selection condition ('when you only care about one thread') and the constraint 'Provide exactly one of topic or id'. It implies the full-history alternative but never names signal_history explicitly, so an agent must infer the sibling to route against.

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