Signal Lab: free data for trading and AI agents

Compare entries

compare_entries

Read-onlyIdempotent

Place the catalog's fields for up to 5 entries side by side. Values are the catalog's own; a field the catalog does not have shows Not in catalog.

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": {
      "slugs": "<slugs>"
    },
    "name": "compare_entries"
  }
}

Input Schema

Name	Required	Description	Default
`slugs`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 30, 2026

TDQS

A3.6/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the basic safety profile is covered. The description still adds real behavioral value by disclosing the provenance of returned values ('the catalog's own') and how absences are rendered ('Not in catalog'), which the annotations do not convey.

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?

Two short sentences with no filler, and the comparison action is front-loaded. The second sentence earns its place by explaining value provenance and missing-field rendering.

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

Completeness3/5

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

With no output schema, the description usefully covers value source and the 'Not in catalog' marker, but it omits what identifies each column (slug? title?) and whether results are ordered as supplied — details an agent needs to interpret the side-by-side output.

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 0% and the single parameter is undocumented in the schema, so the description must carry the load. It does echo the 5-entry ceiling and implies the array elements are entry identifiers, but it never explains what a slug is or where to obtain one.

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?

States a concrete verb and resource: places catalog fields for up to 5 entries side by side. That is clearly distinct from single-entry siblings like get_entry, though the description never names a sibling to contrast with explicitly.

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?

Usage is only implied — the 'up to 5 entries side by side' phrase suggests this is the multi-entry comparison tool rather than a lookup, but there is no explicit 'use this instead of get_entry when...' guidance or any stated preconditions.

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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