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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds real context beyond that: it identifies the underlying endpoint and explains what each returned item's IDs are for (conversation_id as conversation_linkedin_id for messages/replies, recipient_linkedin_id for sends). It doesn't discuss rate limits or pagination edge cases, so not a 5.

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?

Front-loaded with the purpose, then routing guidance, then return-value semantics; every sentence carries information. The parenthetical endpoint reference is slightly dense but not wasteful.

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 filtered list tool with full schema coverage, an output schema, and read-only annotations, the description covers purpose, routing to the sibling, and the meaning of returned IDs. Nothing an agent needs to select or call it correctly is missing.

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 count, unread, starred, archived, account_id, and next_cursor are all documented in the schema; the description only restates the filters and paging at a high level. Baseline 3 is appropriate, though the downstream ID semantics add minor value.

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+resource ('List LinkedIn messenger conversations'), scopes it to the Voyager Messaging GraphQL endpoint, and explicitly distinguishes classic inbox from Sales Navigator threads by naming the sibling salesnav_list_messaging_threads. An agent can tell it apart without opening schemas.

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?

Gives an explicit routing rule: 'Use for the classic LinkedIn inbox (this is the one that matters in 95% of cases); Sales Navigator threads are separate.' The when/when-not and the alternative are both named.

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