@gblin-protocol/mcp-server

quote_safe_swap

Read-onlyIdempotent

Preview ETH→GBLIN buys or GBLIN→ETH sells without executing; get expected output, safe minOut with dynamic slippage buffer (2.5%/4% during Crash Shield), and fee breakdown.

Instructions

Preview a buy (ETH→GBLIN) or sell (GBLIN→ETH) without executing. Returns expected output, safe minOut with dynamic slippage buffer (2.5% normal / 4% during Crash Shield), and fee breakdown. Read-only.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`amount_in`	Yes	Positive decimal. ETH for buy, GBLIN for sell.
`direction`	Yes

Output Schema

TableJSON Schema

Name	Required	Description
`fees`	No
`direction`	Yes
`next_step`	Yes
`amount_in_eth`	No	Buy only.
`cooldown_note`	No
`amount_in_gblin`	No	Sell only.
`slippage_reason`	No
`expected_eth_out`	No	Sell only.
`safe_min_eth_out`	No	Sell only. Pass as minEthOut.
`expected_gblin_out`	No	Buy only.
`safe_min_gblin_out`	No	Buy only. Pass as minOut.
`slippage_buffer_bps`	Yes
`will_revert_with_zero_tolerance`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.1.5Oct 1, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "properties": {
+    "amount_in_eth": {
+      "description": "Buy only.",
+      "type": "string"
+    },
+    "amount_in_gblin": {
+      "description": "Sell only.",
+      "type": "string"
+    },
+    "cooldown_note": {
+      "type": "string"
+    },
+    "direction": {
+      "enum": [
+        "buy",
+        "sell"
+      ],
+      "type": "string"
+    },
+    "expected_eth_out": {
+      "description": "Sell only.",
+      "type": "string"
+    },
+    "expected_gblin_out": {
+      "description": "Buy only.",
+      "type": "string"
+    },
+    "fees": {
+      "type": "object"
+    },
+    "next_step": {
+      "type": "string"
+    },
+    "safe_min_eth_out": {
+      "description": "Sell only. Pass as minEthOut.",
+      "type": "string"
+    },
+    "safe_min_gblin_out": {
+      "description": "Buy only. Pass as minOut.",
+      "type": "string"
+    },
+    "slippage_buffer_bps": {
+      "type": "number"
+    },
+    "slippage_reason": {
+      "type": "string"
+    },
+    "will_revert_with_zero_tolerance": {
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "direction",
+    "slippage_buffer_bps",
+    "next_step"
+  ],
+  "type": "object"
+}

First observedv1.1.2May 25, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: the dynamic slippage buffer (2.5% normal / 4% during Crash Shield) and the fee breakdown returned.

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

Conciseness5/5

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

Two tightly written sentences, front-loaded with the core purpose and return values. Every sentence adds information without repetition.

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?

An output schema exists, so return values need not be explained in full, yet the description still summarizes them. Annotations cover safety, and the description adds the slippage and fee context, leaving no critical gaps for correct invocation.

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 50%: amount_in has a description, but direction has only an enum. The description compensates by mapping buy to ETH→GBLIN and sell to GBLIN→ETH, clarifying the missing half of the parameter semantics.

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?

States a specific verb (preview) and resource (buy/sell ETH↔GBLIN), and explicitly distinguishes from execution with 'without executing'. An agent can tell this is a read-only quote tool separate from swap execution siblings.

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

Usage Guidelines3/5

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

The phrase 'without executing' implies the tool is for previewing before a swap, but it does not name any alternative tool or state when not to use it. No explicit routing to siblings like swap_gblin_to_usdc_jit or preview_steps is provided.

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