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

Annotations already cover readOnly/idempotent, so the description's value-add is the credential-cost disclosure ('never spends credits') and the scope limitation that only bulk-job completion endpoints are returned. It does not address the openWorldHint implication (results can change externally), which keeps it below a 5.

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?

Two short sentences; the scope constraint comes first and the free-call reassurance second. No repetition of the title and no filler.

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, return values need not be described, and the annotations carry the safety profile. What remains slightly uncovered is pagination/result-size behavior for a potentially open-world list, but otherwise the definition is sufficient to call the tool 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?

There is a single optional parameter (timeout_ms) at 100% schema description coverage, so the schema fully documents it. The description adds nothing about timeout behavior, and per the baseline rule this is a 3.

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 and resource (list / webhook endpoints) and narrows the scope to endpoints registered for bulk-job completion events, which is a meaningful qualifier. The verb alone already separates it from create_webhook, delete_webhook, update_webhook and test_webhook, so no explicit sibling routing is needed.

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: call this to see which webhooks are registered. The 'Free: this call never spends credits' note is a useful cost signal that lowers the bar for calling it, but there is no explicit when-not or pointer to alternatives (e.g. use test_webhook to verify delivery).

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