scan_url

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

The readOnlyHint and openWorldHint annotations already establish that this is a safe external fetch, and 'public web page' is consistent with that. The description adds that output includes per-platform previews and fix suggestions, but says nothing about crawling limits, timeouts, auth requirements, or idempotency, so it adds only modest context.

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?

Two sentences with no waste: capability statement first, then the use case. Everything is front-loaded and each clause carries information an agent can act on.

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?

For a single-parameter read-only scanner, the description names the analyzed inputs, the output categories (metadata, per-platform previews, issues with fixes), and the question it answers. Nothing needed to call it correctly is missing, and there is no output schema implying more detail was expected.

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 0%, so the description must carry the url parameter, and it only implies one constraint: the page must be public. It does not explain acceptable formats, whether redirects are followed, or why the 2048-character cap exists, so it partially but not fully compensates for the schema gap.

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 gives a specific verb and resource ('Scan a public web page') plus the exact artifacts produced (Open Graph / Twitter Card metadata, per-platform previews, issues with fixes). That scope separates it from siblings like refresh_preview and get_link_stats, though it never names an alternative explicitly.

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?

It supplies a concrete usage context ('Use it to answer why does my link preview look wrong?'), which is a real routing signal for an agent. It stops short of stating when not to use it or which sibling to prefer for related tasks such as refreshing or generating previews.

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