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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds real value beyond them: the secret is never returned, a missing webhook yields 404, and a personal token is required for auth. That is meaningful operational context for a tool the annotations alone would leave generic.

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?

Three short sentences, front-loaded with the outcome and followed by the usage rule, the secret/404 caveat, and the auth requirement. The first sentence duplicates the title rather than adding information, which is the main slack in an otherwise tight 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?

For a no-parameter, no-output-schema reader, the description covers what it returns (the destination address, never the secret) and the failure mode (404 when unset) plus auth needs. Exact response fields are unstated, but with no output schema that is a minor gap rather than a blocker.

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?

The tool takes zero parameters and the schema is empty with additionalProperties=false, so there is no parameter meaning to add. Baseline 4 applies; the description correctly implies no filtering or identifier is needed.

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 a specific read operation: 'check whether a webhook is set, and to which address', which distinguishes it from setters like set_webhook. The opening sentence is a whimsical restatement of the title, but the second sentence grounds it in a concrete retrieval. It does not explicitly name its sibling set_webhook as the alternative, which keeps it from a 5.

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?

'Use it to check whether a webhook is set' gives clear when-to-use context for a zero-parameter read tool. The 404 case defines the negative outcome, so the agent knows what an empty result means. It stops short of explicit routing language ('use set_webhook instead to create one'), which is the only missing piece.

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