image_registry_data

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

Beyond the read-only and non-destructive annotations, the description discloses that the tool uses the daemon and its cached credentials to resolve the remote descriptor and platform list. It also warns that `auth_config` credentials may be logged verbatim by MCP clients, which is a significant behavioral/security trait not conveyed by annotations alone.

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 well-organized: a one-line primary purpose, a short usage alternative, a concise security note, and a clear args/returns list. Every sentence adds relevant information without unnecessary verbosity, making it both concise and structured effectively.

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 tool is simple (2 params, no output schema), but the description fully covers the needed context: it explains what the tool does, how it works, the return format (dict with Descriptor and Platforms), the security implications, and the alternative tool. With annotations already indicating read-only behavior, this description is complete for the tool's complexity.

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?

Even though the input schema has no descriptions (0% coverage), the tool description compensates with an 'args:' section that explains `repository` as 'Image reference' and `auth_config` as 'Optional registry authentication config.' The security paragraph also elaborates on the purpose and handling of `auth_config`, adding meaning beyond the raw schema.

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 clearly states a specific action ('Get registry data for an image without pulling it') and the mechanism (via the daemon's distribution endpoint). It also distinguishes itself from the sibling tool `registry_manifest` by explicitly mentioning the alternative for direct registry access, which establishes a clear unique purpose.

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 provides explicit guidance on when to use this tool versus alternatives: 'For direct registry access without a daemon use `registry_manifest`.' It also gives security-related usage instructions, advising to prefer `docker login` and leave `auth_config` unset, which clarifies the intended usage context.

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