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

Annotations already declare readOnlyHint=true, and the description adds valuable pagination behavior: persisting nextCursor only after processing items and the effect of empty pages. It does not contradict the annotation and adds context beyond it.

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 sentences with no filler, front-loaded with purpose and followed by compact, essential cursor guidance. Every sentence earns its place.

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 read-only, single-parameter tool with no output schema, the description covers purpose and the key pagination caveat. It lacks an explicit return-shape statement, but the enumeration of event types and mention of `nextCursor` make the interface sufficiently clear.

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 single `cursor` parameter has no schema description (0% coverage), and the description only refers to `nextCursor` without explicitly mapping it to the parameter. It adds partial meaning about pagination but leaves the exact relationship between the `cursor` argument and the `nextCursor` response field to inference.

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 ('Get') and enumerates the resource types ('new replies, mentions and subscribed events'), making the tool's purpose clear. It does not explicitly differentiate from sibling read tools like read_messages, so it stops short of the top score.

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 operational guidance for cursor handling but does not say when to prefer this tool over siblings or when not to use it. The intended usage is implied by 'Get new replies...' but there is no explicit routing or exclusion.

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