Serpstat 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 an excellent job disclosing behavioral traits. It explains data availability requirements (10+ keywords in top-10), error conditions ('Data not found' for new/low-traffic pages), input format requirements (URL must include https://), and operational details (API cost: 1 credit per result row). This goes well beyond basic functionality description.

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?

The description is appropriately sized and front-loaded with the core purpose. Each sentence adds important information about constraints, errors, and costs. However, the final sentence about API costs feels somewhat tacked on and could be better integrated with the preceding content about data availability.

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 tool with 5 parameters, 100% schema coverage, but no annotations and no output schema, the description provides excellent context about behavioral constraints, error conditions, and cost implications. The main gap is the lack of information about return format or what 'competitor URLs' data structure looks like, which would be helpful given no output schema.

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 baseline is 3. The description adds some value by reinforcing the URL parameter requirements ('must include protocol https://') and linking URL quality to data availability, but doesn't provide significant additional parameter semantics beyond what's already well-documented in the schema descriptions.

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 tool's purpose: 'Returns competitor URLs that rank for the same keywords in Google top-10.' It specifies the resource (competitor URLs), the context (Google top-10 rankings), and distinguishes it from siblings like 'get_domain_competitors' or 'get_keyword_competitors' by focusing on URL-level analysis.

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 provides clear context for when to use the tool: 'Best results for established pages with significant organic traffic' and 'The analyzed URL must rank for 10+ keywords in top-10 to have competitor data available.' It also explains when it won't work (new/low-traffic pages). However, it doesn't explicitly mention when to choose this over sibling tools like 'get_domain_competitors' or 'get_keyword_competitors'.

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