# MCP catalogs and agent hosts

> Read complete tool contracts while keeping execution in your host.

Use LLMSlim v0.6.0 MCP sources, context plans, scoped caching, and the optional OpenAI Agents SDK bridge.

Category: Guides & Strategies · Updated: September 2026 · 4 min read

## Install an optional integration

MCP and Agents extras require Python 3.10 or newer. Base planning and text compression remain available without these SDKs.

```bash
pip install 'llmslim[mcp]==0.6.0'
# For the optional Agents SDK bridge:
pip install 'llmslim[agents]==0.6.0'
```

## List, plan, and hydrate

Configure a trusted endpoint explicitly. HTTP is allowed only for localhost development; remote endpoints require HTTPS. Stdio sources accept an executable and literal argument list. Plans default to the full catalog.

```python
import asyncio
from llmslim.mcp import MCPToolCatalogSource, plan_catalog_context, hydrate_plan

async def main():
    source = MCPToolCatalogSource.from_streamable_http(
        'http://127.0.0.1:8000/mcp', source_id='local-tools'
    )
    snapshot = await source.list_tools()
    plan = plan_catalog_context(snapshot)
    schemas = hydrate_plan(snapshot, plan)
    print(len(schemas), plan.metrics.catalog_tokens)

asyncio.run(main())
```

## Freshness and host ownership

The shortest page TTL governs the full snapshot. Private entries are isolated by the caller's cache principal; only explicitly public responses may be shared. Use source.refresh() or source.invalidate() when your host learns a catalog changed. Hydration rejects a plan from a different catalog fingerprint.

> **Selection is not permission:** Never use rankings or fingerprints as authorization. Keep provider credentials and execution policy in the host. Live-model task success is not established by the offline integration benchmark.

## FAQ

### Does this execute MCP tools?

Catalog sources only list tools. The optional Agents bridge requires your async invocation callback; your host remains responsible for authorization, argument validation, and execution.

### Does the default save schema tokens?

No. Full and measure-only plans retain every authoritative schema. Selective exposure is an explicit research-only experiment.

## Related

- [Adaptive Context Planner](https://www.llmslim.app/docs/adaptive-context-planner.md)
- [Getting Started](https://www.llmslim.app/docs/getting-started.md)

Canonical page: https://www.llmslim.app/docs/mcp-catalogs