check_new_messages

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

With no annotations provided, the description carries the burden of behavioral disclosure. It reveals that the operation is one-shot, does not block, and depends on state from 'the last check'—useful behavioral traits beyond the schema. It does not mention whether polling has side effects such as marking messages read, but the core non-blocking statefulness is conveyed.

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 sentences, each earning its place: the first defines the operation and non-blocking behavior, the second states the intended use case. No filler or redundant restatement.

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 simple polling tool with two optional parameters and no output schema, the description adequately conveys what the tool does and when to use it. It could clarify the meaning of 'last check' or the return shape, but the core calling context is sufficiently complete.

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 baseline is 3. Both limit and mailboxId are already described in the schema, and the tool description adds no additional parameter-level meaning or usage nuance.

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 ('Poll') and a specific resource ('new inbound messages received since the last check'), and clearly implies a one-shot, non-blocking retrieval. This differentiates it from the sibling list_inbound_messages by emphasizing the 'since last check' scope.

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?

Provides a clear usage context: 'Use this to monitor an inbox for new email.' It does not explicitly name exclusions or alternatives like list_inbound_messages, but the intended polling/monitoring scenario is unambiguous.

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