fastly_purge_service

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

With no annotations, the description carries the full disclosure burden. It proactively labels the operation as 'high-risk mutation', requires confirmation of serviceId, and mentions the admin authorization key requirement. This goes beyond a typical operation description, though it stops short of detailing side effects like irreversibility or impact on all users.

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 that leads with the most important warning ('High-risk mutation'), then states the action, followed by essential usage notes. Every word earns its place with no redundancy.

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?

The description is adequate for a straightforward purge operation, covering risk and auth requirements. However, it omits details like success/failure reporting, idempotency, or whether a network condition could cause partial purges. For a high-risk mutation, more operational context would improve completeness.

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%, so the description must compensate. It hints at two parameters—serviceId ('confirm serviceId') and authorizationKey ('require MCP_ADMIN_AUTH_KEY')—but is silent on fastlyToken. This leaves one required parameter completely unexplained, failing to adequately define all inputs.

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 precise action ('purge all cached content') on a specific resource ('Fastly service'), with a clear verb that distinguishes it from sibling tools like get_config and set_config. The description is unambiguous about scope and intent.

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 when to use it (to invalidate all cache) and provides cautionary context, but does not explicitly state use conditions, alternatives, or when not to use it. Siblings offer no competing purge tool, so the guidance is implicit rather than explicit.

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