list_yesterday_emails

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

No annotations are provided, so the description carries full burden. It discloses a limit of 100 emails and mentions performance as a rationale, which is useful. However, it does not state whether the operation is read-only, how results are ordered, or what fields are returned, leaving notable behavioral aspects undisclosed.

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?

The description is two concise sentences, front-loaded with the core purpose and a brief performance rationale. No wasted words.

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?

The tool is simple with one optional parameter and no siblings, but the description omits important context such as timezone handling for 'yesterday', result ordering, and what email data is included. It is adequate but leaves several gaps that could affect correct usage.

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 100%, so the schema already documents the limit parameter. The description adds 'Limited to the latest 100 emails' but this conflicts with the schema's configurable limit parameter, potentially misleading the agent into thinking the limit is fixed at 100. This adds negative value rather than clarifying parameter semantics.

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?

The description clearly states the tool fetches emails received yesterday, with a specific verb ('Fetch') and resource ('emails received yesterday'). It is unambiguous and distinguishes this tool from potential siblings by specifying the time 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?

The description implies the tool is for retrieving yesterday's emails but does not explicitly state when to use it versus alternatives, nor any exclusions. With no sibling tools provided, the lack of explicit guidance is less critical, but still a gap.

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