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

Annotations already declare readOnly/openWorld=false and non-destructive, so safety is covered. The description goes further by disclosing the selection rule ('still without their answer, regardless of age') and the pagination contract ('pages continue with nextCursor while hasMore'), which the annotations cannot express.

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?

Front-loaded with the core behavior and kept to two sentences with no filler. The enumeration of returned fields is slightly dense, but every clause carries information rather than restating the name.

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 responsibly enumerates the return payload (chat and link, why it is addressed, related item, message with attachments) and the pagination contract. For a read-only, two-parameter list tool this covers what an agent needs, missing only explicit sibling routing.

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 both parameters are already documented and the baseline is 3. The description adds genuine meaning by stating that pages continue via nextCursor while hasMore, tying the cursor/limit pair to a concrete continuation condition the schema does not state.

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?

States a specific verb and resource: returns messages addressed to the token owner that are still unanswered, with the addressing reason (direct chat, mention, reply). It is clearly distinguishable from chat_read or chat_send, though it never names a sibling to sharpen the contrast.

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?

Gives an explicit trigger condition: 'Useful when the user asks what awaits their reply.' That is clear usage context, but there is no when-not guidance and no named alternative (e.g. chat_read) for unanswered vs. all messages.

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