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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description goes well beyond that by disclosing that there is no quota charge, that the X-API-Key header is required and anonymous callers are rejected, and that it neither reveals webhook secrets nor probes servers.

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?

Front-loaded with purpose, then usage and exclusions, then auth, then return shape — every sentence carries distinct, callable information despite the density. Nothing is redundant with the name or annotations.

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 no output schema, the description carries the return contract itself, enumerating watches[] fields (id, server, webhook_url, active, disabled_reason, last_known, consecutive_failures, last_delivery) and free_tier. Combined with auth and scoping notes, an agent has everything needed to call it 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?

Zero parameters, so the baseline is 4. The description confirms 'No arguments' and adds the quota-cost behavior, but there are no parameter semantics to enrich further.

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 ('List webhook subscriptions') plus the exact scope ('stored for the API key on this request'), including what the listing shows ('delivery health'). This clearly separates it from siblings like check_mcp_server_health and watch_server without needing to open any schema.

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?

Gives explicit when-to-use ('to copy a watch id before unwatch_server, or to see failures') and explicit when-not ('Do not use it to learn if a server is up (check_mcp_server_health) or to create a subscription (watch_server)'), naming the correct alternative for each case.

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