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

Annotations already cover the safe-read profile (readOnly, idempotent, non-destructive). The description adds genuinely new behavioral context: it is 'fail-closed,' requiring trusted key, algorithm, nonce, freshness, replay status, and signature coverage of method/target/content, plus a cost of 0.003 USDC. It does not, however, state the failure/return behavior.

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?

A single dense, front-loaded sentence that packs requirements and cost with no filler. It is run-on and would be easier to scan as a clause list, but every token carries information.

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 security-critical, nested-object preflight with no output schema, the description covers the verification semantics well but omits the event object's role and gives no indication of the outcome on success or failure. Adequate but with clear gaps for an unfamiliar caller.

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 0%, so the description carries the burden. It maps well onto the 'verification' subfields (trusted key, algorithm, nonce, freshness/max_age, replay status, verified_components covering method/target/content). It says nothing about the 'event' object (delivery_id, timestamp, payload), leaving that half undocumented.

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 and resource: a fail-closed webhook preflight/verifier. The resource (webhooks) is distinct from sibling preflights like counterparty_risk_preflight or data_egress_preflight, so an agent can route correctly, though it does not explicitly name a competing sibling.

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?

The word 'preflight' implies use-before-processing a webhook, and the enumerated requirements imply prerequisites, but there is no explicit when-to-use vs. when-not, nor any named alternative (e.g., verify/preflight siblings). Usage is inferable rather than stated.

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