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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered by structured data. The description adds nothing beyond that – no mention of pagination, ordering defaults, or expansion behavior, which are the behaviors an agent would actually need context on.

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 words are technically concise but this is under-specification rather than economy of language. The sentence does not front-load scope, filters, or pagination semantics, so there is nothing useful being kept short.

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?

This is a paginated list tool with a required threadId, an opaque cursor, ordering, and an expand parameter, plus no output schema. The description provides none of the context needed to call it correctly, leaving the entire burden on the schema.

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 high (80%): limit, order, cursor, and expand all carry inline descriptions. Per the rubric, a high-coverage schema establishes a baseline of 3 even when the tool description contributes no parameter meaning, and here it contributes none.

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?

Tautological: description restates name/title.

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?

There is no guidance on when to use this versus messages_get (single message) or messages_history (edit/event history). The scope (all messages in a thread, paginated) is only inferable from the schema's threadId and cursor, not from the description.

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