sigtap Agent Tools

crypto_price

Coinbase spot/buy/sell price with spread percent Free check: https://sigtap-outreach-api.sigtap.workers.dev/preview/tools/crypto-price = 200 demo sample, no wallet. Paid call: 402 challenge -> sign -> retry = settled on-chain. ($0.002 USDC on Base, x402)

Input Schema

TableJSON Schema

Name	Required	Description	Default
`to`	Yes	Quote asset code, e.g. USD
`from`	Yes	Base asset code, e.g. BTC

Output Schema

TableJSON Schema

Name	Required	Description	Default
`buy`	Yes
`pair`	Yes
`sell`	Yes
`spot`	Yes
`spread_pct`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 7, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "buy": {
+      "type": "number"
+    },
+    "pair": {
+      "type": "string"
+    },
+    "sell": {
+      "type": "number"
+    },
+    "spot": {
+      "type": "number"
+    },
+    "spread_pct": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "pair",
+    "spot",
+    "buy",
+    "sell",
+    "spread_pct"
+  ],
+  "type": "object"
+}

First observedSep 5, 2026

TDQS

A3.9/5.0

Behavior4/5

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

With no annotations, the description carries the burden of behavioral disclosure, and it does so well: it reveals the free-tier sample limit, the no-wallet condition, the 402 challenge/sign/retry flow, and the $0.002 USDC fee on Base via x402. Minor gaps remain around error behavior and output specifics, but the core billing and invocation behavior is transparent.

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?

The core purpose is front-loaded, and every clause earns its place: data returned, free demo access, paid settlement mechanics, and cost. The '402 challenge -> sign -> retry' shorthand is terse but compact, not wasteful.

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

Completeness4/5

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

An output schema exists, so return-value documentation is covered structurally. The description supplies the missing operational context: how to sample the tool for free, when payment is triggered, and what the settlement flow looks like. The x402 mechanics could be more explicit, but for a two-parameter price tool this is nearly complete.

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

Parameters3/5

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

The input schema already fully documents both parameters, from and to, with base and quote asset code examples. The description adds no extra parameter-level meaning, so the baseline score of 3 applies.

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

Purpose4/5

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

The description clearly identifies the resource: Coinbase spot, buy, and sell prices with spread percent. It lacks an explicit verb like 'get' or 'fetch,' but the intent is unambiguous and no sibling tool overlaps with crypto pricing, so differentiation is unnecessary.

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

Usage Guidelines4/5

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

The description distinguishes a free 200-sample demo call that requires no wallet from a paid on-chain call, giving the agent a clear path to test before paying. It does not mention alternatives or exclusions, but the sibling list contains no competing price tools, so context is sufficient.

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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