messages_from_sender

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

No annotations exist, so the description must carry the behavior alone; it discloses the 5000-item cap, the return payload (message_ids plus count, summaries of the first 50), and the confirm_count handshake for downstream destructive operations. It stops short of confirming read-only semantics and whether subfolders are included, which leaves a small gap.

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 scope and cap, then the return contract, then the alternative. Two sentences and a clause, all load-bearing, though the tool list in the middle clause is slightly dense.

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 no output schema and no annotations, the description correctly fills the gap by describing the return values and the cap. An agent can invoke and chain it confidently; only subfolder behavior and limit-vs-cap interaction are left unstated.

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 coverage is 0%, so the description must compensate for all three parameters. It conveys sender as an exact address and folder as a single folder, but says nothing about the limit parameter's defaults or how it interacts with the 5000 cap and folder ('inbox' default unstated). Partial compensation only.

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?

Names a specific verb and resource plus exact scope: 'Every message from one exact address in a folder, up to 5000.' The exact-address and single-folder constraints distinguish it clearly from search_messages and the find_* siblings.

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?

Explicitly routes the agent: use this for bulk actions, use search_messages with `from:` for a quick look. It also names the downstream tools this output feeds (archive_messages, delete_messages, move_messages), giving concrete when-to-use and when-not-to-use context.

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