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

The description provides useful behavioral context beyond the annotations: login is required and the operation only updates 'my lastReadAt'. This clarifies the mutation's scope and side effect. It does not contradict the annotations, and the idempotent/non-destructive hints are already covered by annotations.

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, tightly written sentence that front-loads the auth requirement and clearly states the operation and its effect. Every piece of text earns its place; there is no fluff or unnecessary detail.

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?

This is a simple one-parameter mutation tool with robust annotations and full schema coverage. The description adds the two missing pieces an agent needs — authentication requirement and what state changes — making the tool complete enough for correct invocation.

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?

The input schema already has 100% description coverage for conversationId ('会话 id'), so the description does not need to add much. It mentions '某个会话' in passing, which reinforces the parameter's meaning but adds no new semantic detail beyond the schema.

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 states a specific action ('mark a conversation as read') with a precise resource and side effect ('updates my lastReadAt'). This clearly differentiates it from read/list/message tools and leaves no ambiguity about what the tool does.

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 intended use is implied by the verb phrase '把某个会话标记为已读', and it gives a login prerequisite. However, it does not explicitly state when to prefer this over related tools like read_messages or get_conversation, nor does it mention alternative tools for different intents.

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