set_message_flags

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

Annotations already indicate this is a non-read-only, non-destructive operation. The description adds that it modifies flags based on RFC message-id, but does not disclose other behavioral traits like side effects, permissions, or rate limits. With annotations providing a baseline, the description adds modest value.

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 immediately conveys the tool's purpose. No redundant or unnecessary words, and it is front-loaded with the action.

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 tool has no output schema, so the description should ideally mention return values or success/failure behavior. It does not. However, given the tool's simplicity (3 simple parameters), the description is minimally adequate but lacks completeness on what happens after execution.

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 0%, so the description must compensate. It implicitly explains message_id as 'RFC message-id' and mentions 'read and/or flagged status', tying the two boolean parameters to their purpose. However, it does not clearly state that 'read' sets the read flag and 'flagged' sets the flagged flag, leaving some ambiguity.

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 sets read and/or flagged status on a message identified by RFC message-id. It uses a specific verb ('Set') and resource ('flags on a message'), and the RFC message-id identifier distinguishes it from sibling tools like bulk_mark_read which operates on multiple messages.

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?

No guidance on when to use this tool versus alternatives like bulk_mark_read for bulk operations or when not to use it. The description only explains what it does, not the context of use.

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