# Tool-result size governor for MCP — TextForAgents LLC

A client-side output-budget proxy so no MCP server you don't control can blow your agent's context or deadlock its transport.

## Start (self-serve, no operator step)
1. POST /register {"operator": "your-name"} -> {"account_id", "token"} — keep the token; it is your per-customer credential. Identity is canonicalised (NFKC, casefolded, format characters stripped, whitespace collapsed): registering again under a variant of the same identity returns the same account and does NOT re-grant the trial.
2. POST /shape {"route": "list_papers", "args": {...}, "text": "<tool result text>"} — or {"result": <MCP result envelope>} to shape every text block of an MCP result, or {"fixture_tool": "list_papers", "tool_args": {"count": 500}} to rehearse on the built-in fixture population (list_papers, read_log, read_prose, echo_small, big_blob). Response: the shaped window, plus a signed omission receipt on every shaped result: {route, mode, total_bytes, returned_bytes, omitted_bytes, total_records, returned_records, omitted_records, artifact_id, sha256, expires_at, signature}. Billing: the first 100 shaped results are free, one time per operator; after that $0.001/result via x402, or an Operator/Fleet plan. An unshaped (already-in-budget) result passes through free and consumes nothing.
3. Repeat-everything denial: re-firing the identical (route, args) everything-query while its spill lives returns a denial with a signed denial receipt describing the ORIGINAL spill — narrow your args, or fetch a slice. The denial lives exactly as long as its spill: after expiry or eviction the identical query re-opens exactly once (it is shaped fresh and re-registered).
4. POST /fetch-slice {"artifact_id", "offset", "limit"} — a narrower slice of YOUR spilled payload, byte-exact (data_base64) with the full-payload sha256 re-verified on fetch. Errors are clean, never a crash: unknown_artifact (404 — includes artifacts retired early by eviction), artifact_expired (410), invalid_slice_range (400). Receipt expires_at is an UPPER BOUND: quota eviction under the bounded spill store can retire an artifact earlier.
5. POST /budgets {"route", "max_bytes", "max_records", "max_tokens"} sets your per-route ceilings; GET /budgets lists them. Defaults: 32768 bytes / 50 records / 8192 tokens per route.
6. Plans: POST /subscribe {"tier": "operator"} ($9.00, 100,000 shaped results/mo, all agents) or {"tier": "fleet"} ($29.00, 1,000,000 shaped results/mo + per-route budget reports in /account) with an x402 X-PAYMENT header.
7. MCP: POST /mcp (JSON-RPC) — tools shape_result, fetch_slice, verify_receipt — same account token and billing.
8. Receipt keys: GET /verify-key lists accepted signing-key fingerprints (rotation keeps archived keys verifiable). POST /receipts/verify {"receipt": {...}} verifies a signed omission receipt publicly. A receipt is an omission record only — it grants no access and validates no content.

## Limits
Shaping correctness was measured structurally (exact counts, byte-exact re-fetch, forged receipts rejected); a live-model task-completion study was not measured and no task-completion claim is made. Spill storage is bounded per operator; spill artifacts are ephemeral (1 h TTL max). Support: support@textforagents.com.

## Prices
Operator $9/mo per operator · Fleet $29/mo per operator · Per-result API $0.001/result (x402). First 100 shaped results free, one time per operator. No perpetual free tier.