Read eXpress chat history

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: local decryption, one backward page per call, and pagination via nextBeforeSyncId. There is no contradiction with the 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?

Two short, information-dense sentences with no filler. The primary action is front-loaded, and the pagination pointer is a necessary operational detail. Every word 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?

The annotations cover the read-only/idempotent safety profile, but the description omits essential parameter semantics (limit, scope, required chatId) and does not describe the return shape or page boundaries. For a 4-parameter tool with no output schema, an agent cannot reliably assemble correct calls beyond the defaults.

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 0%, so the description must compensate by explaining parameters. It only hints at beforeSyncId's role ('request older pages'), while chatId, limit, and scope remain completely unexplained. An agent would not know what scope means, what limits to pass, or why chatId is required.

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 verb ('Read'), a specific resource ('chat history page'), and a distinctive mode ('locally decrypt'). It also scopes to 'a chat visible to the authenticated user,' which clearly differentiates it from sibling tools like express_send_message (write) and express_list_chats (list).

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 implies the tool is for reading chat history, but it never explicitly contrasts it with siblings or states when not to use it. The only concrete usage guidance is pagination related ('Use nextBeforeSyncId to request older pages'), which helps after the first call rather than for initial tool selection.

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