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

The annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false. The description adds that results are summaries and scoped to an inbox, but it does not explain pagination, limits, cursor behavior, or what happens with large result sets.

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?

It is a single short sentence with the key scope and resource front-loaded. It is efficient, though very terse for a tool with several parameters.

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?

There is no output schema, and the description does not cover pagination, result limits, or direction filtering. For a list tool with four parameters and limited schema descriptions, the definition is incomplete enough that an agent may not know how to page or filter 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 25%, and only inboxId has a schema description, which is essentially just "Inbox ID." The description adds no meaning for limit, cursor, or direction, leaving three parameters undocumented by both schema and description.

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 and resource: "List summaries of messages" scoped to "an inbox." It distinguishes the tool from get_message by saying summaries rather than full messages, but it does not explicitly differentiate from search_messages.

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?

Usage is only implied by "for an inbox," which signals the required inbox scope. It does not state when to use this tool instead of search_messages or get_message, nor does it mention pagination or filtering context.

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