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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions the batch limit (200 URLs) and custom domain support, which are useful behavioral traits. However, it lacks critical details like authentication requirements, rate limits, error handling, or what the response format looks like, leaving significant gaps for a mutation tool.

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 appropriately sized and front-loaded with the core purpose. However, it includes minor redundancy (e.g., repeating 'optional' for parameters already labeled as such in the text) and could be more streamlined. Most sentences earn their place by adding value, but slight editing could improve efficiency.

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 the tool's complexity (batch mutation with multiple optional parameters), no annotations, and no output schema, the description is moderately complete. It covers the purpose, batch limit, domain, and parameter semantics well, but lacks behavioral details like authentication, response format, or error handling, which are important for a mutation 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?

The schema description coverage is 0%, so the description must fully compensate. It provides detailed semantics for all parameters: the required 'urls' array structure, and for each URLItem, it explains 'url' (required), 'slug' (optional with default behavior), 'expiredAt' (format example), 'password', and 'comment' (dashboard display). This adds substantial meaning 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?

The description clearly states the specific action ('batch shorten long URLs'), resource ('U301's short link service API'), and scope ('up to 200 URLs per request'). It distinguishes this as a bulk operation tool with no siblings to differentiate from, making the purpose highly specific and unambiguous.

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 for batch URL shortening with custom domain support, but provides no explicit guidance on when to use this tool versus alternatives (e.g., single URL shortening), prerequisites, or exclusions. With no sibling tools, the context is limited to the implied batch scenario.

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