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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false, openWorldHint=true). The description adds genuinely non-obvious behavior: secret is write-only, is never returned, and is used to produce the GrowSurf-Signature HMAC header on deliveries. It does not disclose rate limits or repeated-call 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?

Five information-dense sentences, purpose front-loaded, each clause carrying real semantics (write-only secret, signature header, env-var fallback). Slight redundancy in restating that payloadUrl is required, which the schema already marks.

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?

An output schema exists so return values need not be explained, and annotations carry the safety profile. The description covers the mutation semantics an agent needs, with the only real gap being the isEnabled flag and any note on how to verify the webhook afterward.

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 only 40% schema description coverage, the prose compensates well for four of five parameters (payloadUrl required, events omitted means no subscriptions, secret write-only signing semantics, campaignId defaulting to the env var). isEnabled is left entirely undocumented in both schema and description, so it is not fully covered.

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 ('Add a webhook to your GrowSurf program'), which cleanly separates it from the update/delete/test webhook siblings by verb alone. It does not name any sibling explicitly, so it falls short of the top mark.

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?

Usage is implied rather than stated: the campaignId fallback to GROWSURF_CAMPAIGN_ID and the 'omit events to subscribe to no events' note give context for calling it, but there is no explicit when-to-use guidance or steering toward growsurf_update_campaign_webhook / delete siblings.

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