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

Annotations cover only readOnlyHint and openWorldHint; the description adds the critical non-obvious trait that this is a paid call (x402, USDC on Base, $0.01 or 1 credit), which an agent must know before invoking. It also describes the returned content in lieu of an output schema, though it omits rate limits and whether a large 'days' window is bounded in practice.

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?

Front-loaded with the payload contents in the first sentence, followed by usage guidance and pricing. Three sentences, no filler, though the pricing clause is somewhat verbose and could be tightened.

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 two-parameter read tool with no output schema, the description adequately covers what is returned and the payment requirement. It is nevertheless incomplete on the parameter side (slug meaning, days window semantics and its 365-day cap), which is exactly what an agent needs to call it correctly.

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 0% and the description never explains either parameter: it does not say that 'slug' identifies the MCP server nor that 'days' sets the lookback window for the checks. The schema supplies only type/default/min/max, so the description fails to compensate for the coverage gap.

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?

Specific verb+resource: 'Timestamped history of Electra Index's live checks for one MCP server', with an enumeration of what the history contains (check results, status transitions, answer rate, tool count, version changes). The time-series framing implicitly separates it from get_mcp_server, but no sibling is named or contrasted explicitly.

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 before relying on a server in production' gives a clear triggering context for the tool. There is no when-not guidance and no named alternative (e.g. get_mcp_server for current status only), so it falls short of the explicit routing a 5 requires.

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