avelino/mcp

Support --dry-run flag for tool calls

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#1 opened on Mar 16, 2026

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clienhancementgood first issue

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Description

When debugging or learning what a server expects, there's no way to see the JSON-RPC request that would be sent without actually sending it.

You have to guess, call the tool, get an error, adjust, and try again. For destructive operations (like send_message on Slack), this is risky — you can't preview what you're about to do.

A --dry-run flag on tool calls would let users inspect the exact request payload before it hits the server.

Contributor guide

Research direction
Add a dry run flag to the tool call command that outputs the JSON RPC request payload without sending it. Look at how the tool call is implemented currently (likely using an MCP client) and modify the flow to conditionally serialize the request and print to stderr or stdout if the flag is passed.
Tech stack
rust
Domain
cli
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustCLI tool development
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60