# Agent Weather Cheapest Model Selector > Agent Weather Cheapest Model Selector is a paid API for AI agents from api.agentweather.io, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-17). Returns the lowest-priced OpenRouter AI model meeting specified constraints (context length, price caps, capabilities), plus a fallback model recommendation. ## Facts - Endpoint: GET https://api.agentweather.io/v1/decide/cheapest-model?utm_source=zero.xyz - Price: $0.003/call - Payment: x402 - Status: unknown - Last checked: 2026-10-17 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/agent-weather-cheapest-model-selector-2cc676bb - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CGMOm85hMpEvrZzE6uTpQ Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently. ## How to call it through Zero Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`): ```sh zero fetch --capability agent-weather-cheapest-model-selector-2cc676bb ``` Example prompt: Find me the cheapest OpenRouter model that supports at least 32k context, vision input, and tool use, with a max input cost of $2 per 1M tokens and max output cost of $6 per 1M tokens — and give me a fallback option too. ## When to prefer this Use this endpoint when you need to programmatically select the cheapest viable AI model from OpenRouter before making an LLM call, especially when cost is a primary constraint and you need a reliable fallback. Prefer this over manual price-checking when filtering by multiple hard constraints (context window, capabilities, vendor allowlists/blocklists, per-job cost caps) simultaneously. ## Known failure modes - No models match the combined constraints — returns empty pick with explanation - Invalid capability enum values cause parameter rejection - Vendor name typos result in empty vendor filter matches - Free-tier models excluded by default if include_free not set to true - Model retiring within exclusion window filtered out silently ## How this service works Use when an agent needs the lowest listed price among models meeting hard needs (context, price cap, capability), plus a fallback reading. Pre-flight reading: the AI model with the lowest listed price on OpenRouter among those meeting your needs (min_context, max_input_per_1m, max_output_per_1m, ma… ## Output Returns a structured response containing: the selected cheapest model (pick) meeting all constraints, a fallback model recommendation, a decision summary, the action to take, and the rules applied during filtering. All fields reflect current OpenRouter listed prices. ## Request schema (JSON Schema) ```json { "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "input" ], "properties": { "input": { "type": "object", "required": [ "type", "method", "queryParams" ], "properties": { "type": { "type": "string", "const": "http" }, "method": { "enum": [ "GET" ], "type": "string" }, "queryParams": { "type": "object", "required": [], "properties": { "vendor": { "type": "string", "description": "comma list of allowed vendors" }, "capability": { "type": "string", "description": "comma list: reasoning, coding, vision-input, image-output, audio, free-tier, tools, structured-output" }, "min_context": { "type": "string", "description": "minimum context length in tokens" }, "include_free": { "type": "string", "description": "true to allow free tiers" }, "exclude_vendor": { "type": "string", "description": "comma list of vendors to skip" }, "allow_disturbed": { "type": "string", "description": "true to allow disturbed vendors" }, "max_input_per_1m": { "type": "string", "description": "max input USD per 1M tokens" }, "max_job_cost_usd": { "type": "string", "description": "max USD for 10k in + 1k out tokens" }, "max_output_per_1m": { "type": "string", "description": "max output USD per 1M tokens" }, "exclude_retiring_days": { "type": "string", "description": "skip models retiring within N days (default 30)" } }, "additionalProperties": false } }, "additionalProperties": false }, "output": { "type": "object", "required": [ "type" ], "properties": { "type": { "type": "string" }, "example": { "type": "object", "required": [ "decision", "action", "summary", "pick", "fallback", "rules" ], "properties": { "pick": {}, "rules": {}, "action": {}, "summary": {}, "decision": {}, "fallback": {} }, "additionalProperties": true } } } } } ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "kind": "pre-flight reading: lowest listed price among models meeting your needs", "pick": { "id": "openai/gpt-oss-20b", "name": "OpenAI: gpt-oss-20b", "role": "pick", "report": "https://api.agentweather.io/v1/models/report?id=openai/gpt-oss-20b", "vendor": "openai", "reasons": [ "lowest standard_job_cost_usd (0.00027) among 185 model(s) that met every filter" ], "vendor_status": "operational", "context_length": 131072, "expiration_date": null, "price_in_usd_per_1m": 0.018, "capabilities_matched": [ "tools" ], "price_out_usd_per_1m": 0.09, "standard_job_cost_usd": 0.00027 }, "rules": { "selection": "pick = minimum standard_job_cost_usd among models passing every filter (ties: i…", "standard_job_cost_usd": "10,000 × pricing.prompt + 1,000 × pricing.completion (USD per token). A fixed r…" }, "terms": "https://api.agentweather.io/v1/terms", "action": "use_pick_keep_fallback", "summary": "openai/gpt-oss-20b at $0.00027 per standard job (10k in + 1k out); fallback inc…", "decision": "go", "fallback": { "id": "inclusionai/ling-3.0-flash-vl", "name": "inclusionAI: Ling 3.0 Flash VL", "role": "fallback", "report": "https://api.agentweather.io/v1/models/report?id=inclusionai/ling-3.0-flash-vl", "vendor": "inclusionai", "reasons": [ "lowest-cost candidate from a different vendor than the pick (inclusionai vs ope…" ], "vendor_status": "unknown", "context_length": 262144, "expiration_date": null, "price_in_usd_per_1m": 0.021, "capabilities_matched": [ "tools" ], "price_out_usd_per_1m": 0.0616, "vendor_status_reason": "no free JSON status endpoint is mapped for this vendor", "standard_job_cost_usd": 0.0002716 }, "issued_at": "2026-10-13T06:36:10.433Z", "disclaimer": "Recorded measurements as of issued_at; may be late, incomplete or wrong; not fi…", "schema_version": "decide-0.1.0-draft" } } ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-weather-cheapest-model-selector-2cc676bb/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from api.agentweather.io](https://www.zero.xyz/host/api.agentweather.io/llms.txt)