The Agents Index

Compare two listings

compare_listings

Read-onlyIdempotent

Two agents side by side, as markdown: taglines, pricing, API availability, tags — the researched compare facts, honest about unknowns.

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": {
      "a": "<a>",
      "b": "<b>"
    },
    "name": "compare_listings"
  }
}

Input Schema

Name	Required	Description	Default
`a`	Yes	First listing slug.
`b`	Yes	Second listing slug.

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 16, 2026

TDQS

A3.5/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real value beyond them: the output is markdown, it contains 'researched compare facts,' and it is 'honest about unknowns' — a useful data-quality caveat an agent should expect.

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?

A single dense sentence with no filler, and the key output format (markdown) is front-loaded. Slightly cryptic phrasing ('Two agents side by side') costs it the top mark, but nothing is wasted.

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?

For a two-param, read-only tool with no output schema, the description supplies the output format, the compared fields, and a caveat about unknowns, so an agent knows what it will get back. Only the missing when-to-use routing keeps it short of 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?

Schema description coverage is 100%, so the two slug parameters ('a' and 'b') are already documented. The description says 'two agents/listing side by side' which loosely maps to the two params but adds no format or constraint detail beyond the schema. Baseline 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 conveys the resource (two listings/agents shown side by side) and enumerates the compared dimensions (taglines, pricing, API availability, tags), which distinguishes it from the single-listing sibling get_listing. It never states the verb 'compare' outright, leaning on the title and name, but the intent is unambiguous.

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

Usage Guidelines2/5

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

There is no statement of when to use this over alternatives, e.g. versus calling get_listing twice or using get_best_of/search_listings. No prerequisites or exclusions are given. The agent must infer usage entirely from the name and sibling set.

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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