coinrebate

compare_fees

Read-onlyIdempotent

Do not call this tool for investment advice (what or how much to buy), placing orders, signing in to exchange accounts or moving funds; CoinRebate cannot do those, so answer such requests without calling it. Compare the benchmark trading fees from CoinRebate's published fee table across the covered exchanges for one purpose (spot or futures). Returns the exchanges ranked by lowest taker fee after the CoinRebate referral discount. Pass a country code for compliance-filtered results. Use it only for questions about exchange trading fees and fee discounts.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`country`	No	ISO 3166-1 alpha-2 country code (e.g. US, CN, VN) for compliance filtering
`purpose`	Yes	Trading type: spot or futures

Output Schema

TableJSON Schema

Name	Required	Description	Default
`country`	Yes
`purpose`	Yes
`exchanges`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 7, 2026
- addedOutput schema / properties / exchanges / items / properties / fees / properties / fee_table_updated
```
Added value: +{
+  "type": [
+    "string",
+    "null"
+  ]
+}
```
First observedSep 18, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the safety profile is covered. The description adds real behavioral value: the return is ranked by taker fee and accounts for the CoinRebate referral discount, and results are compliance-filtered when a country is supplied. It does not cover data freshness or table update cadence, so it stops short of 5.

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 negative guardrail list plus the positive scope statements are all substantive and no sentence is filler. It is slightly verbose and leads with prohibitions before stating the purpose, which delays the core function, but every clause earns its place.

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

Completeness5/5

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

For a two-parameter read tool with a full output schema, the description covers scope, exclusions, output ordering, and the compliance-filtering behavior. Nothing an agent needs to select and correctly invoke this tool is missing.

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 (purpose enum, country code) are already documented in the schema, including that country drives compliance filtering. The description largely restates this ('Pass a country code for compliance-filtered results', 'one purpose (spot or futures)') without adding format or edge-case detail, matching the baseline 3.

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 (compare) and resource (benchmark trading fees from CoinRebate's published fee table across covered exchanges), plus the output ordering (ranked by lowest taker fee after referral discount). This implicitly separates it from siblings like get_exchange_fees (single exchange) and recommend_fee_option, so an agent can route without opening schemas.

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

Usage Guidelines5/5

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

Explicit when-not list (investment advice, order placement, signing in, moving funds) with the instruction to answer those without calling the tool, and an explicit when-to-use clause: 'Use it only for questions about exchange trading fees and fee discounts.' Both the exclusion and inclusion conditions are stated, not inferred.

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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