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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the behavioral nuance that premium products require the appropriate primary inbox, which is useful context beyond the annotations. However, it doesn't disclose what the return structure looks like or how the tool behaves when no inboxes exist, but with annotations covering the safety profile, a 3 is appropriate.

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 sentences with zero waste. The core purpose is front-loaded, and the usage guidance is packed into the second sentence without redundancy. 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?

For a simple list tool with one optional parameter, full schema coverage, and safety annotations, the description is nearly complete. It explains the product scope and the premium-inbox prerequisite. The only minor gap is that it doesn't describe the return format, but with no output schema and a simple list operation, this is a small omission rather than a critical one.

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 the schema already fully documents the single optional account_id parameter. The description doesn't add parameter-specific details beyond what the schema provides, but the schema's description is already rich (explaining when to omit, when to list accounts, and how to choose). Baseline 3 is correct when the schema does the heavy lifting.

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 clearly states the tool lists LinkedIn messaging inboxes and explicitly names the three product types (Classic, Sales Navigator, Recruiter). It distinguishes itself from the sibling linkedin_list_inbox_chats by indicating it should be used before listing inbox chats, and from linkedin_list_conversations by focusing on inboxes rather than conversations.

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 provides explicit usage guidance: use before listing inbox chats or starting Sales Navigator/Recruiter conversations, and notes that premium products require the appropriate primary inbox. This gives the agent clear when-to-use context and implies when not to use it (when you need chats or conversations, use the sibling tools).

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