Spronta MCP Server

generate_signed_url

Create secure, time-limited CDN URLs for images with HMAC-SHA256 signing and optional transformation parameters to control access and delivery.

Instructions

Generate an HMAC-SHA256 signed CDN URL. Requires signing to be enabled.

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": {
      "path": "<path>"
    },
    "name": "generate_signed_url"
  }
}

Input Schema

Name	Required	Description
`projectId`	No	Project ID (UUID). If omitted, uses SPRONTA_PROJECT_ID env var.
`path`	Yes	Image path (e.g. /my-project/hero.jpg)
`params`	No	Transform params as key-value strings (e.g. {w: '800'})
`expiresIn`	No	Expiration in seconds (60–604800)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1Mar 22, 2026

TDQS

B3.2/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the prerequisite 'Requires signing to be enabled,' which is useful context about authentication/configuration needs. However, it lacks details on rate limits, error conditions, what happens if signing isn't enabled, or the format of the generated URL. For a tool that generates signed URLs (a security-sensitive operation), this is insufficient.

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?

The description is extremely concise—two short sentences with zero wasted words. The first sentence states the core purpose, and the second adds critical prerequisite information. It is appropriately sized and front-loaded, with every sentence earning its place.

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

Completeness2/5

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

Given the complexity (generating signed URLs with cryptographic operations), lack of annotations, and no output schema, the description is incomplete. It doesn't explain what the tool returns (e.g., a URL string, error formats), security implications, or detailed behavioral traits. The prerequisite hint is helpful but insufficient for full contextual understanding.

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 description coverage is 100%, so the schema fully documents all 4 parameters (projectId, path, params, expiresIn). The description adds no parameter-specific information beyond what's in the schema. According to scoring rules, when schema coverage is high (>80%), the baseline is 3 even with no param info in the description.

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 states the tool's purpose: 'Generate an HMAC-SHA256 signed CDN URL.' It specifies the cryptographic method (HMAC-SHA256) and resource type (CDN URL), which distinguishes it from sibling tools like 'build_cdn_url' (likely unsigned) and 'upload_image'. However, it doesn't explicitly differentiate from 'update_signing' or 'get_signing_config', which are related to signing configuration.

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 description provides some usage context: 'Requires signing to be enabled.' This implies a prerequisite but doesn't explicitly state when to use this tool versus alternatives like 'build_cdn_url' (for unsigned URLs) or 'update_signing' (to enable signing). No explicit when-not-to-use guidance or alternative tool recommendations are provided.

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

Deploy Server