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

Annotations mark the tool as non-read-only and non-idempotent but say nothing about effects; the description supplies the crucial behavioral facts — cancellation stops queued/future delivery but cannot recall an in-flight HTTP request, and status reports delivery acknowledgements only. Notably it clarifies the scope of 'cancel' despite destructiveHint=false, resolving rather than contradicting that flag.

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 tight sentences, front-loaded with what the tool does, then effect semantics, then the status caveat. No filler; every clause adds discriminating information.

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 and only coarse annotations, the description carries most of the load and does so well for a mutation tool. It could say more about what 'verify' returns on success/failure or whether cancellation is reversible, but nothing critical for correct invocation 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 coverage is 0%, so the description must carry the burden. It explains the token is private, ties subscription_id to the subscription being managed, and maps each operation value to its behavior. It does not add format constraints (64-hex token, UUID subscription_id), but those are already expressed as patterns in the schema.

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 resource (a reply-notification subscription) and enumerates the three operations — status, verify retry, cancel — so the agent knows exactly what the tool does. It is clearly distinguishable from cafe_subscribe_replies, which creates rather than manages a subscription.

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 per-operation guidance, including the max-three-attempts cap on verification retry, which tells the agent when to use 'verify'. It does not explicitly name alternatives (e.g. cafe_subscribe_replies for initial setup) or state when not to call it, so it stops short of full routing guidance.

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