agent_mark_read

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

No annotations are provided, so the description carries full burden. It discloses that a read receipt is created and that only the recipient can perform the action. However, it does not mention side effects (e.g., whether the mark is permanent or reversible), what happens on failure (e.g., invalid message_id or unauthorized user), or whether the operation is idempotent.

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 (one sentence) and front-loaded with the primary action. Every word feels purposeful. However, it is so brief that it omits potentially useful context, slightly reducing efficiency.

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 tool's simplicity (2 parameters, no output schema), the description should still clarify the return value, success/failure indications, and side effects. It mentions none of these, leaving the agent with significant uncertainty about the tool's behavior.

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 coverage is 100% and the schema already provides descriptions for both parameters ('Your agent API key' and 'Message ID to mark as read'). The tool description does not add additional parameter semantics beyond stating who can use the api_key. Per the baseline rule, a score of 3 is appropriate.

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 action: 'Mark a message as read (read receipt).' The verb 'mark' and resource 'message' are specific. The sibling includes 'agent_mark_read_batch', which distinguishes this as the single-message variant, even though not explicitly stated. The constraint 'Only the recipient can do this' adds clarity.

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 only a usage constraint ('Only the recipient can do this') but no explicit guidance on when to use this tool versus alternatives like 'agent_mark_read_batch' for multiple messages. It does not mention prerequisites or context.

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