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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real context beyond that: provenance ('Official MCP Registry, tested live by Electra Index') and the specific fields returned, including live check status, which tells the agent results are freshness-verified.

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 tight sentences: purpose and source first, return fields second, usage cue last. Every clause carries information and nothing is padded.

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?

With no output schema, the description helpfully enumerates the returned fields, and it covers purpose, source, and usage. Remaining gaps are minor: no differentiation from the sibling search/curation tools and no hint about result-count/pagination behavior tied to limit.

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 coverage is 67%: query and hosted_only are described in the schema, but limit (default 5, max 10) is not. The description adds no parameter-level detail such as query phrasing tips or how limit affects results, so the schema is doing essentially all the work.

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?

States a specific verb and resource ('Search the Electra Index catalogue of MCP servers') and names the underlying data source, so the agent knows exactly what corpus is being queried. It does not differentiate itself from close siblings like best_mcp_servers_for or get_mcp_server, which keeps it from a 5.

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?

'Use it to find a server for a task' with concrete example queries ('web scraping', 'invoices', 'postgres') gives clear usage context and shows the expected query style. No when-not condition or explicit alternative (e.g. best_mcp_servers_for for curated picks) is named, so it stops short of a 5.

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