list_messages

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

Even though readOnlyHint is already set, the description adds meaningful behavior: it returns compact cards with specific fields, orders them newest first, optionally includes activity log items, and explicitly states that reading does NOT mark anything as seen. This goes beyond the annotation and gives the agent accurate expectations for side effects.

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?

Three sentences, no filler. The core purpose is front-loaded, return behavior is summarized compactly, and the no-seen side effect is stated in one clear sentence. Every sentence 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?

For a list-style tool with one required parameter and full schema coverage, the description supplies everything needed: what is returned, ordering, optional activity log behavior, the pointer to get_message for full bodies, and the read-only side effect. No output schema exists, so describing the compact card shape is particularly valuable.

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%, with kind, limit, origin, and workspace_id each already well-documented. The description adds useful context about return format and ordering but does not need to explain parameter semantics since the schema carries that burden. Baseline 3 is appropriate.

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 and resource: 'List the messages (and optionally the activity log) in a workspace.' It adds the portal's Activity tab context and explicitly routes to get_message for full bodies, clearly distinguishing this tool from its sibling get_message.

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 gives clear context for when to use this tool ('the portal's Activity tab') and tells the agent to call get_message for a full body. It also clarifies that reading does NOT mark messages seen, implicitly distinguishing it from mark_messages_seen, though it stops short of explicit when-not-to-use rules or a broader alternatives list.

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