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 fully covered by structured data. The description adds only the scope restriction 'accessible private conversations'; the 'does not create/add participants' clause largely restates what readOnlyHint already conveys, with no added detail on pagination or result characteristics.

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 short sentences, zero filler, with the positive scope stated first and the exclusion second. Every clause carries routing value and nothing is redundant padding.

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?

With an output schema present, return values need not be described, and annotations cover the safety profile, so the definition is nearly self-sufficient for a two-parameter list tool. The only mild gap is that the notion of 'accessible private conversations' is never elaborated (e.g., owned vs. joined), leaving scope boundaries slightly open.

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%: both 'after' (cursor semantics, filter stability, first-page behavior) and 'limit' (range 1-100, default 50) are fully documented in the schema. The description adds no parameter meaning beyond that, so the baseline of 3 applies.

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?

Clear verb+resource ('List ... conversations') with two scoping qualifiers: 'existing' and 'accessible private'. An agent immediately knows this is a read-only enumeration of private conversations. It does not, however, explicitly distinguish itself from list_docs/list_projects/list_tasks siblings beyond the resource noun.

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 second sentence provides negative scoping ('Does not create conversations or add participants'), which implicitly tells the agent this is not the write path. However, it names no positive trigger condition and no explicit alternative tool, so the when-to-use guidance remains inferential rather than stated.

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