[feiiiiii5]

Description

Fixes #4432.

The prompt configuration supports every Parameter type, but MCP clients send prompts/get values as strings. An integer argument such as {"count":"3"} currently fails parameter parsing instead of producing the prompt.

Decode non-string prompt parameters from their JSON representation in the existing Argument wrapper, then use the existing parameter parser. This also preserves parameter-source selection, defaults and declared validation. Document the wire representation and cover the actual HTTP request path.

Validation on Go 1.27.3:

• Original implementation: 10 unit cases fail with type errors; the HTTP integration fails with JSON-RPC -32602 for the integer argument.
• Updated implementation: go test -race ./internal/prompts/... -count=1 and go test ./tests/prompts/custom -run TestMCPPromptsIntegration -count=1 -timeout=10m pass.
• Golangci-lint 2.15.0 reports 0 issues for both affected packages; formatting and git diff --check pass. go.mod and go.sum are unchanged.
• Tests cover typed scalars, false/zero values, arrays/maps, defaults, valueFromParam, and JSON-looking literal strings. Full repository and external database suites were not run.

PR Checklist

• Reviewed CONTRIBUTING.md.
• Opened Non-string prompt arguments reject string-valued MCP input #4432 before writing code.
• Reviewed the entire diff.
• Relevant tests and linter pass.
• Relevant unit-package coverage increased from 85.3% to 86.7% (prompts: 95.0% to 95.6%).
• Updated the prompt argument documentation.
• Breaking change (!): not applicable.

[gemini-code-assist]

Code Review

This pull request introduces support for parsing and converting string-encoded arguments passed by MCP clients into their declared parameter types (such as integers, floats, booleans, arrays, and maps) using JSON decoding. It updates the Argument.Parse method to handle this conversion, adds comprehensive unit tests covering various data types and edge cases, and integrates a new typed prompt test in the integration test suite. There are no review comments, and the implementation looks solid, so I have no feedback to provide.