hub_repo_info

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

Goes well beyond annotations by disclosing auth behavior ('sends no auth and does NOT read the local Docker credential store') and failure modes for private repos. ReadOnlyHint annotation is consistent with the read-only nature described, with no contradiction.

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?

Every sentence earns its place: a one-line summary, a concise behavioral note with alternatives, and a structured args/returns block. No fluff, well-organized, and scannable.

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?

Despite no output schema, the description lists typical return fields ('description, star_count, pull_count, last_updated, is_private, etc.'), covers auth/error behavior, and contextualizes alternatives. Fully sufficient for a simple metadata-fetch tool.

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?

With 0% schema description coverage, the description fully compensates by explaining the `repository` parameter with examples ('library/alpine' or 'myorg/myimage'), adding format and naming conventions beyond the bare 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?

Description opens with a specific verb+resource pair: 'Fetch Docker Hub metadata for a repository.' It distinguishes from siblings by explicitly redirecting tag-related queries to `registry_tags` and `hub_tags`, making the tool's unique scope clear.

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?

Provides explicit usage constraints ('Public repos only', 'private repos return 404/401') and explicitly names alternatives for different needs ('use registry_tags for tag lists... hub_tags for Hub tag details'). This is clear when-to-use and when-not-to-use guidance.

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