set_message_read_status

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

With no annotations, the description carries the full behavioral burden. It does disclose the key trait, an explicit approval gate that is emphasized as 'this exact action', which is meaningful context. However, it says nothing about reversibility (marking read is undoable), permission requirements, error/failure behavior, or side effects on unread counts.

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 short sentences, front-loaded with the action and followed by the safety condition. No filler, no redundancy with the schema.

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?

For a simple state-toggle tool with no output schema, the description plus the fully documented schema covers what an agent needs to call it correctly, including the approval gate. Minor gaps remain around failure modes and reversibility, but nothing essential is missing.

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%, with each of the five parameters documented, including the const-constrained user_approved flag. The description adds no syntax, defaults, or format detail beyond the schema, so the 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?

The description names a specific verb and resource ('Mark a message read or unread'), which is unambiguous on its own. It does not, however, differentiate itself from the adjacent sibling set_message_flag_status, so the agent must infer the boundary between read-state and flag-state operations.

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 a clear, explicit precondition: 'Only call after the user explicitly approved this exact action.' That is genuine when-to-use guidance. It stops short of naming alternatives or stating when not to use it (e.g. bulk operations), so it is strong but not complete.

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