Follow announcement channel

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

Annotations already indicate this is a write operation (readOnlyHint=false) but not destructive (destructiveHint=false). The description adds the behavioral detail of 'subscribing' which implies a linking action without destruction. It does not disclose permissions required or side effects like rate limits, but it is consistent with annotations.

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 a single, well-structured sentence that immediately states the action and purpose. It is front-loaded and contains no extraneous information. Every word earns its place.

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?

Despite the absence of an output schema, the description and full parameter documentation provide enough context for a simple subscription operation. It could mention that 'guild' is optional, but the schema already indicates this. Overall, it is sufficiently complete for its complexity.

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?

The input schema has 100% coverage (all three parameters have descriptions). The tool description does not add any additional meaning beyond what the schema provides. The baseline is 3, and there is no extra value from the description.

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 clearly states the action ('subscribe') and the resources ('channel', 'announcement channel'), and explains the effect ('crossposted messages from the source appear in the target'). This distinguishes it from sibling tools like crosspost_message, which does the crossposting itself.

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?

The description gives no guidance on when to use this tool versus alternatives. It does not mention prerequisites (e.g., user must have manage channels permission) or when not to use it (e.g., if the source is not an announcement channel). There is no explicit context for choosing this over other subscription-related tools.

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