list_registries

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

With no annotations, the description carries the full behavioral burden. It discloses that the tool lists all configured instances and that it is legacy/backward-compatibility-oriented with a performance tradeoff. It does not describe the response format, but for a zero-parameter listing tool this is a minor omission.

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 two sentences with no wasted words. The main purpose is front-loaded, and the backward-compatibility note and resource recommendation are placed after the core statement.

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?

Given zero parameters, no output schema, and a straightforward operation, the description is mostly complete. It names an alternative resource and gives a reason to prefer it, though it does not specify what the returned list contains beyond 'configured Schema Registry instances.'

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?

There are no parameters to document, so the baseline is 4. The description adds no parameter-specific detail, but none is needed here.

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 states a specific verb and resource: 'List all configured Schema Registry instances.' It is clear about what the tool does, but it does not explicitly differentiate itself from sibling tools like get_registry_info or list_subjects, so it relies on the phrase 'all configured' to imply the scope.

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 explicitly says the tool is maintained for backward compatibility and recommends using the 'registry://names' resource instead for better performance. This gives clear guidance on when to use the tool versus the alternative, which is exactly what agents need.

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