read_thread

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

readOnlyHint=true already establishes the safe-read profile, so the bar is lower. The description usefully adds ordering semantics ('oldest first') and the recency window ('most recent count messages'), which annotations do not convey, but it says nothing about how ordering interacts with a capped count or whether older messages are retrievable.

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?

One sentence, no filler, and the key scoping information (most recent, per-conversation, oldest-first order) is front-loaded. Nothing needs trimming and nothing essential is buried.

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?

An output schema exists, so return-value explanation is not required, and the tool is low complexity with only two parameters. The description covers the core behavior adequately; only edge cases (count exceeding available history, behavior when thread_id is invalid) are absent.

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 0%, so the description must carry parameter meaning. It does clarify `count` as the number of most-recent messages and the returned ordering, but leaves the schema default of 20 unmentioned and says nothing about `thread_id` beyond the name.

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?

Specific verb ('Read') plus a precisely scoped resource ('the most recent `count` messages of one conversation'), which is clear enough to separate it from list_threads (enumerating conversations) and send_sms (writes). It does not name those siblings explicitly, but the resource framing makes the distinction inferable.

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?

No explicit when-to-use or when-not-to-use guidance and no mention of any alternative tool, despite having three siblings. The agent must infer from the name alone that this is the tool for reading messages within an already-known thread rather than listing threads.

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