lob_cancel_postcardCancel a postcard before its send_date so it is never mailed (and not billed). Fails if the send window has passed. Lob API: DELETE /v1/postcards/{id}.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Postcard id (psc_…) to cancel. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the destructiveHint annotation, the description explains consequences: the postcard is never mailed and not billed. It also specifies the failure condition (send window passed), providing full behavioral disclosure.
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 concise sentences, front-loaded with the essential action. No unnecessary words; every sentence adds value.
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 cancel tool with one required parameter and no output schema, the description covers the necessary context: when to use, what happens, and failure condition. No additional information is needed.
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?
With 100% schema description coverage, the schema already fully documents the 'id' parameter. The description adds no additional semantic value beyond what the schema provides.
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 explicitly states 'Cancel a postcard before its send_date', providing a clear verb and resource. It distinguishes itself from siblings (e.g., create, list, get) by focusing solely on the cancel operation.
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 gives a clear condition: use before send_date, and notes failure if the window has passed. While it does not explicitly list alternatives, the context among siblings (no other cancel tools) makes the guidance sufficient.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Every tool targets a distinct resource and action, with clear verb-noun names like create_address and verify_us_address. There is no overlapping functionality, and even similar operations (e.g., list for different resources) are distinct.
All tools share the 'lob_' prefix and follow a consistent verb_noun pattern (e.g., create_postcard, list_letters, verify_intl_address). Multi-word nouns use underscores, maintaining uniformity throughout.
With 18 tools, the set covers the primary mail fulfillment operations—address management, postcards, letters, checks, self-mailers, and address verification—without feeling bloated or sparse. The count is well-suited to the domain.
The tool set has notable gaps: no create_check or create_self_mailer, no cancel for letters or checks despite being referenced, no update/delete for addresses, and only list for templates. These missing operations will likely cause agent failures in common workflows.