update_message

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

The description adds significant behavioral context beyond the annotations, including patch semantics, atomic application, order of operations (read/flag before move), and IMAP/Gmail specifics. Annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=true) are consistent with the described behavior of updating and moving messages.

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 efficiently structured, front-loaded with the main purpose, followed by essential details on semantics, order of operations, and deprecation. Every sentence adds value, with no redundancy or fluff.

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 complexity (8 parameters, atomic operations, IMAP implications, Gmail nuances), the description covers all essential aspects: atomicity, patch semantics, order, replacement of previous tools, and deprecation info. The presence of an output schema fills any gaps about return values.

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 provides detailed explanations for each parameter (e.g., account, flagged, gmail_mode). The description's mention of 'Patch semantics' adds overarching context, but does not enhance individual parameter meanings beyond what the schema already offers.

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's function: 'Update one or more messages: change read state, flag, and/or move, in one atomic call.' It also explicitly distinguishes itself from sibling tools by noting it replaces previous separate tools like mark_as_read, move_messages, and flag_message.

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 provides explicit context for when to use the tool, such as atomic updates and replacing previous tools. It also details order of operations and IMAP requirements. However, it does not explicitly state when not to use it, though usage is implied for multiple updates.

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