check_service_zipCheck whether Fold serves a given ZIP code. Returns service availability, the market name (LA/SF), and a list of pickup window options that can be passed to book_residential_pickup. book_residential_pickup only accepts ZIPs this tool reports as served.
| Name | Required | Description | Default |
|---|---|---|---|
| zipCode | Yes | 5-digit US ZIP code, e.g. "90210" or "94103". ZIP+4 and full addresses are accepted; the 5-digit ZIP is extracted. |
Changes observed during successful MCP inspections.
Input schema / properties / zipCode / descriptionPrevious value: -"5-digit US ZIP code, e.g. \"90210\" or \"94103\"."New value: +"5-digit US ZIP code, e.g. \"90210\" or \"94103\". ZIP+4 and full addresses are accepted; the 5-digit ZIP is extracted."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds value beyond them by disclosing the return contents (availability, market, pickup windows) and the downstream precondition on book_residential_pickup, which is precisely the behavioral context an agent needs before chaining calls.
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, front-loaded with the purpose and followed by the output shape and the sibling dependency. Every sentence earns its place with no redundancy.
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?
There is no output schema, so the description's enumeration of the return values is essential and present. With the input format handled in the schema and the downstream booking constraint stated, an agent has everything needed to call and chain this tool correctly.
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% and the single zipCode parameter is fully documented there, including ZIP+4 handling and extraction behavior. The description adds no parameter-level detail beyond the schema, so the baseline 3 applies.
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 and resource (check Fold's ZIP coverage) and enumerates the return payload: service availability, market name (LA/SF), and pickup window options. This is clearly distinguishable from siblings like get_service_info or book_residential_pickup.
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?
Establishes a concrete usage relationship: the pickup window options it returns 'can be passed to book_residential_pickup' and that tool 'only accepts ZIPs this tool reports as served', implying this is a pre-flight gate. It does not explicitly exclude or compare against any other sibling, so it falls short of a full when/when-not statement.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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