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

There are no annotations, so the description carries the full burden. It only says 'parse' and gives no information about how irrelevant schema fields are treated, what happens on invalid URLs, or the return format. The schema hints that some fields are 'discarded,' but that is not in the tool description.

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 a single 10-word sentence that is front-loaded with the action, resource, and result. There is no filler or repetition, making it highly concise and easy to scan.

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?

With no annotations, no output schema, and a 9-parameter schema containing several seemingly unrelated fields, the one-line description is insufficient. It omits the return shape, error behavior, and guidance on how to treat parameters other than 'url', making the tool harder to invoke 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?

Schema description coverage is 100%, so the baseline is 3. The description adds meaning by clarifying that the 'url' parameter should be a GitHub URL and that the output is owner/repo. However, it does not address why the schema includes many unrelated parameters such as city, feed, host, json, path, zone, and query, leaving ambiguity about their role.

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 ('parse'), a specific resource ('GitHub URL'), and the expected result ('owner and repo'). This clearly distinguishes the tool from sibling shape tools like domain-shape or figma-url-shape by naming the GitHub URL domain.

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 usage: call this when you need to extract owner and repo from a GitHub URL. However, it does not explicitly state when not to use it, mention alternatives, or provide exclusion criteria, though the purpose statement itself gives basic guidance.

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