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

Annotations already indicate readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the tool is known to be a non-destructive, idempotent write. The description adds the partial-update behavior, which is useful, but does not mention side effects, permissions, or handling of omitted fields beyond the implicit 'only send changed fields'.

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, concise sentence that front-loads the core action and key constraint. It is not verbose, though the list of fields could be more precise and aligned with schema names.

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?

Given the tool's complexity (13 parameters) and lack of an output schema, the description is insufficient. It does not explain what the tool returns, whether omitted fields retain their previous values (though implied), or any prerequisites or side effects. The partial-update guidance is helpful but incomplete for such a broad update tool.

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 only 46%, so the description needs to compensate for undocumented parameters. However, it omits several parameters (keywords, show_schedule, allow_offline_download, chat_server_id, chat_channel_id) and uses vague terms like 'visibility' instead of is_public and 'community chat link' instead of chat_platform/server/channel. It does not provide enough clarity to make all 13 parameters understandable.

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 verb 'Update' and the resource 'existing channel', and lists specific updatable fields (name, description, visibility, category, language, age rating, community chat link), which distinguishes it from create_channel and archive_channel. It is specific and unambiguous.

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 instruction 'Only send the fields you are changing' is a useful usage guideline for how to call the tool, but it does not explicitly state when to use this tool versus alternatives like create_channel or archive_channel. The usage context is implied by 'existing channel'.

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