HALOWERK: Verify a signed webhook from GitHub, Stripe, Shopify, Slack, Svix or a plain HMA

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

The description goes well beyond the annotations (readOnlyHint, openWorldHint, destructiveHint) by disclosing security and behavioral details: constant-time comparison, timestamp tolerance window, returning the exact signed string for debugging, and the requirement for byte-for-byte body preservation. It also explains the consequences of re-serialization, which is critical for correct use. The annotations are consistent with the described read-only verification 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?

The description is front-loaded with the core purpose, but it repeats pricing information three times (Kostenpflichtig, Hoechstens, and Preis at the end) in a way that feels redundant. The technical explanation is valuable but could be trimmed to a more concise format. The structure is reasonably organized but not every sentence earns its place, so it is not a model of conciseness.

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?

The tool has 8 parameters, no output schema, and supports multiple providers. The description covers major pitfalls (body serialization, timestamp tolerance, signing string order) but does not fully describe the return value beyond 'returns the string that was signed'. It also does not address error handling or what happens when verification fails, which is important for an agent to know given the absence of an output schema. Thus it is adequate but has clear gaps for this complexity.

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?

With 100% schema coverage, the baseline is 3, but the description adds valuable semantics beyond the schema. It explains that providers build signing strings differently (body-only vs. prepending timestamp, id, or version), which directly maps to parameters like timestamp, message_id, and signature. It also clarifies why the body must be exact, enriching understanding of the 'body' parameter. However, it does not detail each parameter individually, so it falls short of a 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?

The description clearly states the tool's action: 'Verify a signed webhook' and enumerates specific providers (GitHub, Stripe, Shopify, Slack, Svix) as well as plain HMAC. This is a specific verb+resource that distinguishes it from sibling tools like jwt_verify, which handles JWT tokens rather than webhook signatures.

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 description provides clear context for when to use the tool: any time a signed webhook from the listed providers needs verification. It does not explicitly mention when not to use it or name alternatives, but the provider list and the distinctive description of signature construction give sufficient situational guidance. The note about passing the body exactly as received is also a usage hint.

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