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

Annotations only supply readOnlyHint=true, so the description carries real additional weight: it discloses ordering (oldest to newest), pagination direction semantics, and the meaning of the hasMore response field. It adds no rate-limit, auth, or size caveats, keeping it short of 5.

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 compact sentences, front-loaded with the primary behavior and then the hasMore semantics; nothing is padded. The semicolon-heavy phrasing is slightly dense but every clause 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?

With no output schema, the description usefully covers the key return signal (hasMore) and pagination behavior, which is what an agent needs to iterate. It does not describe the message object shape, so it is not fully complete, but the essential pagination contract is there.

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%, so the baseline is 3, but the description genuinely adds meaning by explaining that after returns newer messages in the requested direction and how the boundaries relate to ordering. This clarifies the cursor parameters beyond their terse schema descriptions.

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 opens with a specific verb+resource ('Returns chat messages') and qualifies it by cursor direction, so an agent can immediately tell it apart from write-side siblings like chat_send or chat_message_update. It stops short of naming any sibling explicitly, so it does not reach the top of the scale.

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 clear operational context: no cursor returns the latest messages, an after cursor walks forward to newer ones (e.g. replies), implying before for older. It never states when NOT to use it or points to an alternative tool, so it lacks the exclusions a 5 would require.

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