happyfox_list_contact_custom_fieldsList contact custom fields: id, type, choices and required flag. Use the ids as c-cf-. HappyFox: GET /api/1.1/json/user_custom_fields/.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Input schema / $schemaPrevious value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint=true already establishes the safe-read profile, and the description adds value beyond it: the specific fields returned (id, type, choices, required flag), the 'c-cf-<id>' identifier convention callers must use, and the backing endpoint GET /api/1.1/json/user_custom_fields/. With no output schema, this return-shape disclosure is genuinely useful.
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 tight clauses: purpose + returned fields, then the id convention, then the endpoint. Front-loaded with the verb and resource, no filler sentences.
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 parameterless read with no output schema, the description covers purpose, returned fields, id format, and endpoint. Minor gaps remain (pagination, ordering, empty-result behavior), but nothing essential to correct invocation is missing.
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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline for a parameterless definition is 4. The c-cf-<id> note pertains to identifiers returned, not to invocation inputs.
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+resource ('List contact custom fields') and enumerates what each entry contains (id, type, choices, required flag). The 'contact' scope implicitly separates it from the sibling happyfox_list_ticket_custom_fields, though that sibling is never named explicitly.
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?
No explicit when-to-use or when-not-to-use guidance and no named alternative. The only guidance is a downstream usage hint ('Use the ids as c-cf-<id>'), which tells the agent how to consume the output rather than when to call the tool.
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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