Read-only endpoints for crates.io ecosystem intelligence.
Created by @sdhilip200 (Dhilip Subramanian).
Use as an MCP bundle
This CLI ships an MCPB bundle for one-click MCP extension installs where supported.
To install:
- Download the
.mcpb for your platform from the latest release.
- Double-click the
.mcpb file and follow your MCP host's install flow.
Pre-built bundles ship for macOS Apple Silicon (darwin-arm64) and Windows (amd64, arm64); for other platforms, use the manual config below.
If you can't use the MCPB bundle, install the MCP binary and configure it manually.
go install github.com/mvanhorn/printing-press-library/library/developer-tools/crates-io/cmd/crates-io-pp-mcp@latest
Add to your MCP host config:
{
"mcpServers": {
"crates-io": {
"command": "crates-io-pp-mcp"
}
}
}
Quick Start
1. Install
See Install above.
2. Verify Setup
crates-io-pp-cli doctor
This checks your configuration.
3. Try Your First Command
crates-io-pp-cli crates get mock-value
Usage
Run crates-io-pp-cli --help for the full command reference and flag list.
Paths & environment variables
This CLI separates local files into four path kinds:
| Kind | Contents |
|---|
config | User-editable settings such as config.toml and saved profiles |
data | Durable local data such as data.db |
state | Runtime state such as persisted queries, jobs, and teach.log |
cache | Regenerable HTTP/cache files |
Each kind resolves independently. The ladder is:
- Per-kind env var:
CRATES_IO_CONFIG_DIR, CRATES_IO_DATA_DIR, CRATES_IO_STATE_DIR, or CRATES_IO_CACHE_DIR
--home <dir> for this invocationCRATES_IO_HOME for a flat relocated root- XDG env vars:
XDG_CONFIG_HOME, XDG_DATA_HOME, XDG_STATE_HOME, XDG_CACHE_HOME
- Platform defaults matching existing installs
For containers and agent sandboxes, prefer a single relocated root:
export CRATES_IO_HOME=/srv/crates-io
crates-io-pp-cli doctor
Under CRATES_IO_HOME=/srv/crates-io, the four dirs resolve to /srv/crates-io/config, /srv/crates-io/data, /srv/crates-io/state, and /srv/crates-io/cache.
MCP servers do not receive CLI flags from the host. Put relocation in the host env block:
{
"mcpServers": {
"crates-io": {
"command": "crates-io-pp-mcp",
"env": {
"CRATES_IO_HOME": "/srv/crates-io"
}
}
}
}
Precedence matters in fleets: an ambient per-kind variable such as CRATES_IO_DATA_DIR overrides an explicit --home for that kind. Use CRATES_IO_HOME or the per-kind variables for durable fleet relocation; treat --home as the weaker per-invocation lever.
Relocation is one-way. Unsetting CRATES_IO_HOME does not move files back to platform defaults, and doctor cannot find files left under a former root. Move the files manually before unsetting relocation variables.
Existing installs keep working because the platform-default rung matches the legacy layout. Run crates-io-pp-cli doctor --fail-on warn to check path warnings in automation.
Commands
crates
Manage crates
crates-io-pp-cli crates get - Get crate metadatacrates-io-pp-cli crates search - Search crates
Output Formats
# Human-readable table (default in terminal, JSON when piped)
crates-io-pp-cli crates get mock-value
# JSON for scripting and agents
crates-io-pp-cli crates get mock-value --json
# Filter to specific fields
crates-io-pp-cli crates get mock-value --json --select id,name,status
# Dry run — show the request without sending
crates-io-pp-cli crates get mock-value --dry-run
# Agent mode — JSON + compact + no prompts in one flag
crates-io-pp-cli crates get mock-value --agent
Agent Usage
This CLI is designed for AI agent consumption:
- Non-interactive - never prompts, every input is a flag
- Pipeable -
--json output to stdout, errors to stderr
- Filterable -
--select id,name returns only fields you need
- Previewable -
--dry-run shows the request without sending
- Read-only by default - this CLI does not create, update, delete, publish, send, or mutate remote resources
- Offline-friendly - sync/search commands can use the local SQLite store when available
- Agent-safe by default - no colors or formatting unless
--human-friendly is set
Exit codes: 0 success, 2 usage error, 3 not found, 5 API error, 7 rate limited, 10 config error.
Health Check
crates-io-pp-cli doctor
Verifies configuration and connectivity to the API.
Configuration
Run crates-io-pp-cli doctor to see the resolved config, data, state, and cache directories. The platform-default config path is ~/.config/crates-io-registry-pp-cli/config.toml; --home, CRATES_IO_HOME, and per-kind env vars can relocate it.
Static request headers can be configured under headers; per-command header overrides take precedence.
Troubleshooting
Not found errors (exit code 3)
- Check the resource ID is correct
- Run the
list command to see available items
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