Subscribe

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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=true, and destructiveHint=false. The description adds value beyond them by confirming idempotency in plain language and disclosing a quota cost of 51 units, which is useful operational context.

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?

The description is front-loaded, consisting of two short sentences plus a quota line. Every element earns its place: the core action, the idempotency reassurance, and the cost 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?

For a simple two-parameter mutation with rich annotations and an output schema, the description is nearly complete: it covers the action, idempotency, and quota. The only notable omission is explicit usage guidance relative to sibling tools, which keeps it from full completeness.

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 both 'channel' and 'my_channel' in detail. The description adds no parameter-specific meaning beyond what the schema provides, making the baseline score of 3 appropriate.

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?

The description states a specific verb and resource: 'Subscribe the authorized user to a channel.' This clearly distinguishes the tool from the sibling 'unsubscribe' and from read-oriented tools like 'list_subscriptions' without needing to name them.

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?

There is no explicit guidance on when to use this tool versus alternatives such as 'unsubscribe' or 'list_subscriptions.' The statement 'Already being subscribed is fine' is behavioral context, not usage guidance, and no exclusions or preconditions are given.

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