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

Annotations already declare destructiveHint=true and idempotentHint=true, and the description restates idempotency (slight redundancy) but adds genuinely new consequence information: a stopped monitor requires a new subscription to resume watching. That is a non-obvious outcome an agent needs before calling a destructive tool.

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 short sentences, front-loaded with the core action, then the key-identity constraint, then the consequence. No filler and nothing buried.

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 cover the safety profile. The description supplies the destructive consequence and key requirements; the only remaining gap is guidance on sibling alternatives for managing subscriptions.

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%, so the schema already documents id, ifMatch and idempotencyKey in detail. The description's note that names/endpoint IDs are not cancellation keys largely repeats the schema's id description, and ifMatch and idempotencyKey are left entirely to the schema, so no value is added beyond baseline.

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 ('cancelling one Port OS event subscription') and immediately constrains scope to an exact ID sourced from subscription_list or subscription_inspect. This lets an agent distinguish it from subscription_inspect, subscription_list and subscription_label_edit without opening a 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?

Clearly explains how to obtain the key (from subscription_list or subscription_inspect) and warns that names, source endpoints and catalog events identify a subscription but are not cancellation keys. It lacks an explicit statement of when to prefer this over sibling tools like subscription_label_edit, so it stops short of full alternative routing.

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