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

Annotations declare readOnly/idempotent/non-destructive/openWorld, but the description adds substantial behavior beyond them: it is a paid x402 endpoint ($0.03 USDC on Base), editions are not published daily so the date must be checked in /health, and the two-step payment handshake (call with no payment_header first to get the challenge, then resubmit with the signed header). It also clarifies the calling agent's own wallet pays, never the server.

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 [PAID] tag and usage routing, and every sentence carries information. It is dense with parentheticals and repeats the payment mechanics across the body and the closing sentences, so it is slightly longer than strictly needed.

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?

No output schema, but the description enumerates the returned fields (curator judgment, buyer_value, action_hint, sources, multi-day continuity). For a paid, single-optional-param read tool, the payment flow, freshness caveat, and return content are all covered, leaving nothing an agent needs 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% and the nested payment_header field is already fully documented in the schema, so baseline would be 3. The description adds marginal workflow meaning by restating the free first call and the requirement to resend the SAME business arguments with the signed header, reinforcing the parameter's intended use.

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 resource (the most recent stored Daily Agent Signal edition) and its content scope (curator judgment, buyer_value, action_hint, sources), and explicitly names the siblings it is not (signal_delta, signal_day, signal_history). An agent can distinguish it from all four signal_* siblings 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?

Gives explicit when-to-use (start here if you hold no brief yet; want the most recent stored edition) and when-not (already hold an earlier brief and want only changes → signal_delta; one past date → signal_day; several full days → signal_history). The alternative routing is fully specified with conditions.

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