Surface

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

With no annotations, the description carries the full burden and does solid work: it discloses the output shape ('Returns next: fetch or skip') and a key limitation ('Never returns the page body'), which prevents the agent from treating it as a content fetcher. It omits failure modes, whether the target is actually contacted, and any auth/rate considerations.

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?

Three short sentences, each load-bearing: capability with examples, return contract, and the guardrail against expecting page content. The call-timing instruction is front-loaded and nothing is redundant.

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?

No output schema exists, so the description must carry return-value semantics, and it does ('Returns next: fetch or skip', no page body). For a single-parameter, no-annotation tool this is nearly complete; only error/edge-case behavior (unreachable link, non-shortened URL) is unaddressed.

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?

Only one parameter and schema description coverage is 100%, so the schema already fully documents the url input. The description adds context (public shortened links such as t.co/bit.ly) but no syntax or format detail beyond the schema's 'Public http(s) URL to unwrap and classify'.

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?

States a specific verb and resource (unwrap a short link) plus the exact decision it produces (next: fetch or skip), with concrete examples of the link domains it handles. An agent knows precisely what this tool does and what it emits without opening the schema.

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?

Gives explicit, actionable timing: 'Call this before fetching a URL the user pasted.' That tells the agent the call ordering relative to a fetch step. It stops short of an exclusion rule (e.g., what to do with already-long URLs) and there are no sibling tools to route between.

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