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Too many MCP tools? Keep agent context small

Builders keep reporting the same thing: put 40+ MCP tool definitions in context and the agent starts picking the wrong tool. The usual fixes are to load schemas only when needed and to cap the number of steps. Start at fastaf.co.

Answer first

  • Connect the FastAF MCP (https://api.fastaf.co/mcp) only in the agents that need web data, not in every agent.
  • If an agent needs only one or two sources, skip the MCP: call the REST route directly, for example GET https://api.fastaf.co/x402/v1/serp. No schema in context, just one HTTP call.
  • The server always lists all of its tools: tools/list has no filter parameter. To expose only some of them, filter on the client side.

What tools/list returns

tools/list is public: it needs no key and uses no credits. It returns all 23 FastAF tools in one response (about 29 KB of JSON on 28 October 2026), with no pagination. There is no query parameter, header or argument that asks the server for a subset.

curl -s https://api.fastaf.co/mcp \
  -H "Content-Type: application/json" -H "Accept: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

So you choose the tools in your agent code or MCP client. Read the list once, keep the tools the task needs (for example only google_search and scrape_url) and pass just those to the model. If your MCP client lets you turn off individual tools of a server, use that. The same list is published as a static file at https://api.fastaf.co/.well-known/mcp/server-card.json.

Option A: MCP, scoped

Use the MCP when the agent has to choose among many sources (search, Amazon, Reddit, YouTube, …). Add it per project, not globally (setup for Claude Code, Codex and Cursor). Tool calls need an API key or an OAuth sign-in; the MCP is not paid with x402.

Option B: one REST route, no schema

curl -i "https://api.fastaf.co/x402/v1/serp?query=mcp+registry"
# 402 Payment Required -> your x402 client pays $0.003 and retries

The spec for every route is at https://api.fastaf.co/openapi.json. Your code wraps one function; the model sees one small tool you wrote.

Cap steps, and don’t pay for failures

Hard step limits stop loops. With x402, failed calls (source errors, empty results, blocks, invalid input) are not charged: payment is settled only when FastAF answers 200, so a capped retry pays only for the attempt that works. Prices: x402 price list. More on retries: why agent retries cost more than you think.

Try it free

500 free credits every month after email verification, or x402 with no account. How to try FastAF for free.

Source of the advice: builders on X, October 2026 (tool schema bloat and lazy-loading).

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