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

The description discloses a genuine side effect that the structured data does not: an unknown type/id may be created empty. That is valuable context exceeding the annotations. But it conflicts with readOnlyHint=true, since creation modifies state, so the behavioral picture an agent gets from annotations alone is wrong; disclosure is good, consistency is not.

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 sentences, front-loaded with the primary outcome before the caveat, with no padding. The raw HTTP path 'POST /api/v2/chat/channels/{type}/{id}/query' is marginal value for an agent choosing a tool, which keeps it from a 5.

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?

With no output schema, the description carries the return-value burden and does so adequately: config, members, and recent messages. It omits ordering/pagination behavior for the message list, but for a 3-param read with full schema coverage this is close to complete.

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 type, id and messages_limit (default 25, max 300) are already fully documented in the schema. The description adds only that recent messages are returned alongside state; it explains no parameter beyond what the schema already says. 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?

States a specific verb and resource plus the returned payload: fetch a single channel's state (config, members) and its most recent messages. The singular 'single channel' implicitly separates it from the plural sibling stream_query_channels, but no sibling is named explicitly, so it stops short of a 5.

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 gives one important usage caveat (the get-or-create semantics: reads an existing channel, may create one empty if the type/id is new), which is real guidance. However it never states when to prefer this over alternatives such as stream_query_channels or stream_get_message, so the when-to-use routing is left to inference.

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