Apollo Proxy MCP Server

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: it's a read operation (implied by 'List'), returns ISO 3166-1 alpha-2 country codes, and mentions the 190+ country support scope. It doesn't mention rate limits, authentication needs, or pagination, but provides solid context for a listing tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with zero waste: first sentence states purpose and scope, second sentence specifies return format. Every word earns its place, and information is front-loaded appropriately for a simple tool.

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

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

For a simple listing tool with one optional parameter and no output schema, the description provides good completeness: purpose, scope, return format, and service context. It could benefit from mentioning when to use versus siblings, but covers the essential context given the tool's low complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already fully documents the single optional parameter with its enum values and default. The description doesn't add any parameter-specific information beyond what's in the schema, meeting the baseline expectation for high schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb ('List') and resource ('available proxy exit countries'), specifies the service ('Apollo'), and distinguishes from siblings by focusing on country listing rather than fetching or status checking. It provides specific scope information (190+ countries, residential proxy exits).

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

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

The description implies usage context (when you need to know available proxy exit countries) but doesn't explicitly state when to use this tool versus the sibling tools (proxy_fetch, proxy_status). No explicit alternatives or exclusions are provided, leaving usage decisions to inference.

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