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

Goes well beyond the readOnly/idempotent/destructive annotations: it discloses the failure mode (404, not charged), expected latency (under 1 s), cost (USD 0.001, no free tier), and a security caveat to treat returned page text and on-chain strings as untrusted data. That is substantive operational context an agent cannot get from annotations alone.

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 outcome summary, then pricing, latency, error and security notes in a compact block. Slightly redundant, since 'state, checks left and the history of verdicts' is immediately restated in the 'Returns ...' sentence, costing a bit of tightness.

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 an output schema present it need not re-explain return shapes, yet it still covers error behavior, latency, cost, and data-trust guidance. For a single-parameter read tool, an agent has everything needed to decide and invoke correctly.

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% and the single watch_id parameter is already documented as 'the watch_id returned at creation'. The description reinforces this implicitly but adds no format, length, or sourcing details beyond the schema, so baseline 3 is appropriate.

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?

Names a specific verb (read) and specific resource (read-back watch), and enumerates exactly what is returned: state, checks left, last verdict, per-check results and webhook attempts. This cleanly separates it from the sibling create_readback_watch without needing 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?

Frames it as the read counterpart to create_readback_watch ('the watch_id returned at creation') and states the unknown-id behavior ('404 (not charged)'), giving clear retrieval context. It stops short of explicit when-not-to-use or naming alternatives, so it lands at 4 rather than 5.

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