Sign channel auth

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

Annotations cover the safety profile (readOnlyHint=true, openWorldHint=false). The description adds real context beyond that: it is a pure computation mirroring the auth endpoint's output, plus the presence-channel channel_data requirement. It doesn't state whether it produces side effects (it doesn't, implied by annotations) or the exact return shape, but the added behavioral context is solid.

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 the core action, then use cases, then the one conditional requirement. No wasted words.

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 no-output-schema tool, the description adequately conveys what is produced ('exactly as your auth endpoint would return it') and documents the input requirements. Only the literal return type/format is left implicit, which is a minor gap given the deterministic nature of the operation.

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 100%, so the schema already documents all three parameters with examples. The description reinforces the presence/channel_data link, but that fact is already in the schema's parameter description, so it adds little 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 precise verb and resource: compute the auth signature for a private- or presence- channel subscription. It is immediately distinguishable from all siblings (list_channels, get_channel, publish_event, watch_channel), none of which involve signing.

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 clear when-to-use context: 'testing an auth flow or debugging a signature mismatch.' It also flags the presence-channel condition for channel_data. No explicit when-not guidance or named alternatives, but the usage intent is unambiguous.

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