Mark Message as Read

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

Annotations already cover the safety profile: idempotent, non-destructive, open-world, and not read-only. The description adds the 'blue checkmarks' effect and confirms a return value. It doesn't discuss edge cases like already-read messages, but with annotations in place this is acceptable. No contradiction.

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 extremely concise: two sentences plus a short args list and a return statement. The purpose is front-loaded, and every word earns its place. 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?

For a simple two-parameter tool with no output schema, the description covers the action, input, and return type. The only minor gap is the vagueness of 'Confirmation' as a return description, but this is not critical for such a straightforward operation.

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 baseline is 3. The description repeats message_id's semantics but adds no new information beyond the schema. response_format is fully documented in the schema, so the description's omission is fine.

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 uses a specific verb and resource: 'Mark a received WhatsApp message as read' and adds the observable effect ('shows blue checkmarks'). This clearly distinguishes it from sibling tools, which are all send/get/update/list 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?

The description makes it clear this is for received messages (marking them as read), which is the primary usage context. It doesn't explicitly state when not to use it or name alternatives, but the sibling tools are obviously different operations, so the context is sufficient. Missing explicit exclusions prevents a 5.

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