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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral detail: results are ordered newest-first and purged message bodies surface as text null with body_purged true, which an agent could not learn from the annotations or schema. It omits pagination behavior, noting only indirectly via the schema's starting_after.

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 short sentences, front-loaded with the core action, then ordering, then the edge case. No filler, repetition, or restatement of the tool name.

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 three-parameter, fully documented read tool with no output schema, the description covers the action, the sort order and the null-body edge case, which is what an agent most needs. It would be complete with one clause on pagination or on how it relates to get_conversation.

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 documents id, limit (1-100, default 50) and starting_after (next_cursor). The description adds only the implication that id refers to a conversation rather than a message, which is useful but marginal over the schema baseline.

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 and resource ('List messages') scoped to a conversation, which is unambiguous against siblings like send_message or get_conversation. It does not explicitly say how it differs from get_conversation, which also returns conversation data, so it falls short of a 5.

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 the object described ('The transcript, newest first'), with no statement of when to prefer this over get_conversation or list_conversations, and no prerequisites or exclusions. An agent can infer the use case but gets no routing guidance.

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