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

With no annotations, the description carries the full burden and it does disclose key behaviors: ownership requirement, the effect on subsequent post calls, and the fact that read operations remain functional. It could add idempotency or error details, but it goes well beyond a bare 'close channel' statement.

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?

Two tightly packed sentences: the first states the action and restriction, the second gives the observable behavioral outcome. No filler, and the most important information is front-loaded.

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 tool with no annotations and no output schema, the description covers purpose, authorization, and post-condition behavior. It does not describe return values or what happens on repeated close attempts, but the essential information for invoking it correctly is present.

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_id and tenant_key adequately. The tool description adds no parameter-level meaning beyond what the schema provides, so the baseline 3 applies.

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 uses a specific verb and resource ('close a group channel') and immediately identifies the owner-only restriction. It is clearly distinct from sibling operations like open, freeze, and unfreeze, and the stated post/read behavior further disambiguates it.

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?

It states the tool is owner-only, which is a clear access condition, and explains the practical consequence: posting will fail with channel_closed while reading continues to work. It does not explicitly name alternatives like host.channel.open or freeze, but the usage context is clear enough.

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