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

Annotations already declare destructive=true, idempotent=true, openWorld=false, so the safety profile is covered; the description then adds context annotations cannot express — repeats are no-ops returning 'watch not found', get_api_key is a prerequisite, no contact with the MCP server, and no check quota is consumed. It is consistent with idempotentHint rather than contradicting it.

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?

Four compact sentences, each carrying distinct information (scope, when-to-use, when-not/alternatives, idempotency and preconditions). The core action is front-loaded and nothing is 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 one required string parameter, no output schema, and annotations carrying the mutation profile, the description closes the remaining gaps: the return shape {deleted: id}, the auth prerequisite, and the error behavior for unknown ids. Nothing needed to invoke it correctly is missing.

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?

Schema description coverage is 100% and the parameter's own description already covers the 'w_… id from list_watches, not a server registry name' semantics. The description's 'Pass id from list_watches, not a server name' is a restatement rather than added meaning, so the baseline 3 applies.

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 ('Delete one webhook subscription for this Toolweather API key') plus the side effect of dropping pending deliveries. An agent can distinguish it from watch_server (create), list_watches (read), and check_mcp_server_health without consulting 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 positive triggers ('stop alerts or free a watch slot') and explicit exclusions with alternative routes: use delete-then-watch_server to change a URL, and check_mcp_server_health to check health. The alternatives are named rather than implied.

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