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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, covering safety. The description adds a valuable behavioral caveat: message IDs are scoped to their chat and chat_id must be retained for subsequent actions (get/edit/delete/forward/reaction). This goes beyond annotations and helps agents avoid misuse.

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 efficient sentences with no redundancy. The first sentence front-loads the core purpose and scope; the second adds a critical usage caveat. 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?

Given 8 parameters, no output schema, and low parameter coverage, the description is incomplete. It does not describe the return structure (e.g., list of messages with fields) or pagination behavior in detail. The scoping caveat is helpful, but the missing parameter semantics and return format leave significant gaps for an agent to call this tool correctly.

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 only 38% (3 of 8 parameters have descriptions). The description does not compensate; it only mentions 'full V2 filters/pagination' without detailing after, before, cursor, offset, or limit. Parameters like cursor and offset remain undefined in both schema and description, leaving agents to guess their semantics.

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 ('List') and resource ('messages') scoped to a known chat, with 'full V2 filters/pagination' indicating comprehensive functionality. Clearly distinguishes from siblings like messaging_list_chats (lists chats) and message_get (gets a single message), and from other providers' list tools via the 'messaging_' prefix.

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?

Implies usage when you have a known chat_id ('in a known chat') but does not explicitly name alternatives or exclusions. An agent can infer it is the right tool for listing messages within a chat versus listing chats, but no direct comparison or when-not guidance is provided.

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