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FourA - HTTP request via rotating proxies

foura_proxy
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Route HTTP requests through a rotating proxy pool with automatic retry. Overcome 403 errors, captchas, and geo-blocks by trying multiple proxies until success.

Instructions

Route an HTTP request through FourA's proxy pool with automatic retry across multiple proxies. Per-host proxy rating picks proxies most likely to succeed for the target. Use when foura_single returns 403, captcha, or geo-blocked content. Typical latency 1-5s. The response includes the encoded proxy ID that succeeded ('proxy' field) - reuse it in foura_single.proxy or foura_browser.proxy to pin follow-up requests to the same exit IP, or pass it in ignoreProxies to skip this exit on the next rotation. Escalate to foura_browser if all proxies fail or the page needs JavaScript rendering. When the trigger is a tier-1 WAF challenge (Vercel Security Checkpoint, Cloudflare 'Just a moment', Akamai Bot Manager), set maxTries to 25-30 - the default 5 will usually be too low for these targets. Distinguish from country / ASN allowlist denials (country-licensed bookmakers, government sites): there rotation never helps regardless of maxTries - after ~30 failed attempts on the same block, stop climbing and pivot strategy instead.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
requestYesThe inner HTTP request to send through each proxy attempt. Validation rules here determine when a proxy is treated as failed and retried.
maxTriesNoMaximum proxy rotation attempts before giving up (default 5, max 90). Default 5 is sized for lightly-blocked sites. Raise to 25-30 for tier-1 WAF challenges (Vercel Security Checkpoint, Cloudflare 'Just a moment', Akamai Bot Manager) - most rotations on these targets need this range. If still blocked after 30 attempts, the gate is likely country / ASN allowlist (not solvable by rotation) - pivot strategy instead of climbing to 60.
timeout_msNoOverall timeout across all rotation attempts in ms (default 45000, max 120000). Must be positive.
ignoreProxiesNoEncoded proxy IDs (base36 strings like "4DZ3VE") OR proxy URLs to exclude from rotation. Both forms are accepted.
offload_largeNoIf true, response bodies >= 50KB are written to disk and returned as a resource_link instead of inlined. Default false.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
codeNoStable error code for retry classification. One of: ssrf_blocked, upstream_non_json, output_validation_failed, bad_request (400), auth_failed (401), forbidden (403), not_found (404), rate_limited (429), at_capacity (503), service_disabled (503), service_unavailable (503), upstream_error (>=500), upstream_client_error (other 4xx), upstream_unknown (defensive).
dataNoDecoded response body. Omitted when offloaded.
errorNoHuman-readable error message
proxyNoBase36 ID of the pool exit that succeeded (e.g. `4DZ3VE`). Reuse on next call: pass to foura_single.proxy or foura_browser.proxy → same exit IP. Pass to foura_proxy.ignoreProxies → skip this exit on future rotations.
totalNoOuter total time in seconds (proxy selection + retries + the successful inner attempt). Float.
limitsNo
statusNoHTTP status code from the target (from the succeeding proxy attempt). `0` indicates every attempt failed before any HTTP response (DNS / connection refused / timeout) - check the `error` field for the underlying reason.
currentNo
headersNoResponse headers per redirect hop, as an array of objects. Each entry has `result.{version, code, reason}` plus arbitrary header-name keys whose values are strings (or arrays of strings for multi-value headers like Set-Cookie / Link).
requestNoEchoed PrRequest from upstream PrResponseError
serviceNo
retryAfterNo
size_bytesNoTotal offloaded body size in bytes
total_timeNoPer-attempt wall-clock duration of the succeeding inner request
offloaded_resource_uriNofoura-mcp://payload/<uuid>
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Adds behavioral context beyond annotations: typical latency 1-5s, response includes 'proxy' field for reuse, retry behavior, failure criteria (validate), and explanation of per-host proxy rating. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Description is dense with useful information but well-organized: purpose first, then usage context, then parameter advice. Slightly long but every sentence adds value; conciseness could be improved by splitting into sections.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given tool complexity (5 parameters, nested objects, output schema exists) and high schema coverage, description covers all essential aspects: purpose, when to use, failure handling, latency, and parameter guidance. No gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% so baseline is 3. Description adds extra value on parameter usage (e.g., maxTries defaults and tuning, ignoreProxies usage, validate for fine-grained control), justifying a 4.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states 'Route an HTTP request through FourA's proxy pool with automatic retry across multiple proxies' and distinguishes from siblings foura_single and foura_browser by referencing them as alternatives for specific failure modes.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use (foura_single returns 403, captcha, geo-blocked), when to escalate (foura_browser if all proxies fail or JS needed), and parameter tuning for WAF challenges vs country allowlist denials.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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