AgentFuel

Check a Solana transaction before signing (Presign Guard)

presign_check

Read-only

Green, orange or red verdict for a Solana transaction your bot is about to sign, such as the buy after a rug-check. Red: do not sign. Orange: ask the user first. Nothing is signed or sent. Powered by Presign Guard (presign-guard.fizzl.eu, by Fizzl: fizzl.eu), which has the full report with reasons.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "transaction": "<transaction>"
    },
    "name": "presign_check"
  }
}

Input Schema

Name	Required	Description	Default
`intent`	No	What the transaction should do, e.g. "buy 0.1 SOL of <mint> on pump.fun"
`transaction`	Yes	The base64 wire transaction about to be signed

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 4, 2026

TDQS

A3.9/5.0

Behavior3/5

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

Annotations already declare readOnlyHint and openWorldHint; the description usefully reinforces this with "Nothing is signed or sent" and discloses the third-party dependency (presign-guard.fizzl.eu), which is real added context for an external call. It omits latency, rate limits, failure/error behavior and what a green verdict does not guarantee.

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 verdict scale is front-loaded in the first sentence and the safety disclaimer follows immediately; every sentence carries information. The promotional parenthetical with two URLs is mild overhead but also serves as the provenance/attribution signal.

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?

With no output schema, the description correctly takes on the job of explaining the return value (three-tier verdict plus pointer to a fuller report). For a two-parameter read-only tool this is nearly complete; only error and edge-case behavior is left unspecified.

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?

Schema coverage is 100%, so both parameters are already documented, and the description adds no detail about the transaction encoding or how the free-text intent is used in scoring. The phrase "such as the buy after a rug-check" only loosely hints at the intent field, leaving the baseline of 3 appropriate.

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 and resource: a green/orange/red verdict on a Solana transaction the bot is about to sign. The scope (pre-signing check of the transaction itself, not the token) separates it from rugcheck, injection_check and x402_check.

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?

Clearly frames the moment of use ("a transaction your bot is about to sign, such as the buy after a rug-check") and gives actionable response rules for two of the three verdicts (red: do not sign, orange: ask the user first). It never names a sibling tool or states when not to use it, so routing to rugcheck vs presign_check is only implied.

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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