Save a contact's zone

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

With no annotations, the description carries the behavioral burden. It discloses the replacement/upsert behavior ('Saving the same name REPLACES'), the return payload (resolved zone and local time), and the 5-contact quota. These are genuinely useful non-obvious behaviors.

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?

Three compact sentences, each earning its place: purpose, return behavior, and replacement/quota caveat. The most important information is front-loaded.

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 input schema covers the parameters, and the description compensates for the missing output schema by stating what the call returns. Behavioral caveats like replacement and quota limits are also covered. Minor gaps like error handling do not undermine usability for a simple setter.

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?

All four parameters already have individual schema descriptions, so the baseline is 3. The description adds little beyond saying 'zone and working hours' and the fact that the name is the key for replacement, so it meets but does not exceed that baseline.

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 action ('save'), a specific resource ('one person's zone and working hours'), and the intended benefit ('so later calls can name them'). This clearly identifies the tool's job and distinguishes it from sibling tools like contacts_list.

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?

Gives clear context for when to use it: when saving a contact's zone/working hours for later calls. It does not explicitly contrast with alternatives or name prerequisites, but the use case is clear enough to select this tool correctly.

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