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

With no annotations, the description carries the full behavioral burden and does well: it discloses pricing ($0.002 USDC on base), the no-account/no-API-key model, the two-step handshake, and the 90-day retention depth. It stops short of rate limits, error behavior, or what a probe record contains, but the payment and retention traits are meaningful context beyond schema.

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?

It is front-loaded with the resource name and the payment terms, which is good. But the final sentence ('This is the part nobody who started later can reconstruct.') is pure sales copy that consumes space without adding actionable information, and the pricing line would fit better after the data description.

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 and no annotations, the description must stand alone, and it largely does: data scope, retention window, granularity, and access mechanics are all covered. The main gap is return shape — 'probe by probe' hints at per-record output but the format is never specified.

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 parameters are already documented with their purpose and price. The description restates the omit-supply payment semantics without adding format details (e.g., header encoding, what the requirements response looks like). Baseline 3 is appropriate when the schema does the heavy lifting.

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 the resource and its scope precisely: 'The 90-day probe record for one service, probe by probe.' An agent knows it retrieves per-probe uptime data for a single target. However, it never distinguishes itself from the near-twin sibling get_liveness_history, leaving a real risk of wrong-tool selection.

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?

It gives explicit invocation guidance for the x402 flow ('call without payment to receive requirements, then call again with payment'), which is genuinely useful. But it offers no when-to-use versus alternatives guidance — nothing says when to choose this over get_liveness_history or get_endpoint_alerts, which is the more important routing question.

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