first_last_message

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

Annotations already indicate read-only, non-destructive, and closed-world behavior. The description adds valuable context by specifying the sentimental use case and clarifying that it retrieves both first and last messages, which helps the agent understand the tool's behavioral intent beyond the basic safety hints.

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 front-loaded with the core functionality in the first sentence, followed by illustrative examples that reinforce the use case. Both sentences are purposeful, with no redundant or vague language, making it efficiently structured.

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?

Given the tool's low complexity (single parameter, no output schema) and rich annotations, the description is mostly complete. It explains the purpose and usage context well, but could slightly enhance completeness by mentioning potential limitations (e.g., data availability for old contacts) or the output format, though not strictly required.

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?

The input schema has 100% description coverage, fully documenting the 'contact' parameter. The description does not add any parameter-specific details beyond what the schema provides, so it meets the baseline score of 3 for high schema coverage without extra semantic value.

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's purpose: retrieving the first and last messages exchanged with a contact. It uses specific verbs ('exchanged', 'lookups') and distinguishes from siblings by focusing on sentimental use cases rather than statistical or operational queries like 'check_new_messages' or 'search_messages'.

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 provides clear context for when to use this tool ('sentimental lookups') with concrete examples. However, it does not explicitly state when not to use it or name specific alternatives among siblings, though the examples imply it's for personal reflection rather than data analysis.

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