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

The annotations already indicate readOnlyHint=false and destructiveHint=false, so the description adds no additional behavioral context. It does not disclose side effects, error behavior (e.g., missing id), or any requirements beyond the basic update action, but this is acceptable given the annotations cover the core traits.

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 directly states the action and the affected fields. It is well-structured and contains no unnecessary information, making it easy for an agent to parse.

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?

The description is sufficient for a simple update operation. Since there is no output schema, return values are not expected. However, it does not mention what happens if the id does not exist or if no updateable fields are provided, which could be useful context, but is not strictly necessary for basic usage.

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?

All six parameters are described in the schema with 100% coverage, and the tool description enumerates the fields that can be updated. Parameter purposes are clear enough for an agent to understand what each field represents, including the separate alert level and notification flag.

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 tool updates an existing message's text, context, notification flag, or alert level by id. It uses the specific verb 'Update' and the resource 'message', distinguishing it from create_message, delete_message, and other message-related tools in the sibling list.

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 does not explicitly mention when to use this tool versus alternatives, such as create_message or mark_message_read. It implies usage for modifying an existing message, but provides no direct comparison or conditions to guide selection among sibling tools.

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