Refresh the registry index

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

With no annotations present, the description carries the full behavioral burden, and it discloses the key traits: the operation is an immediate network re-download, and the registry would otherwise refresh on a cache TTL timer. This tells the agent the tool is a forced early refresh rather than an independent or destructive action. It stops short of describing failure behavior or blocking semantics, but for a zero-parameter maintenance operation this is adequate disclosure.

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?

A single sentence front-loads the action ('Re-download the MCP registry index') and appends only the one piece of context that matters (the auto-refresh behavior). There is no wasted text and the most decision-relevant information is first.

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 zero-parameter, no-annotations, no-output-schema tool, the description adequately explains what the tool does and why a manual call is needed. It does not describe the return value, but a sync trigger's return is low-information and the description is sufficient for both selecting and invoking the tool 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?

The tool takes zero parameters, so the schema trivially covers 100% of parameter documentation and there is no semantic burden for the description to carry. The baseline of 4 for zero-parameter tools applies.

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 uses a specific verb ('Re-download') and a specific resource ('the MCP registry index'), making the operation unambiguous. The title reinforces the same concept, and the tool is clearly distinct from siblings that search, describe, list, and call MCP servers/tools rather than maintaining the registry index itself.

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 parenthetical '(otherwise refreshed automatically when the cache TTL expires)' conveys the precise condition under which a manual call is warranted: when fresh data is needed before TTL expiry. It implies that under normal conditions the tool need not be invoked, which is clear usage context, though it names no explicit alternatives or when-not-to-use conditions.

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