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

Annotations already establish that this is a non-read-only, non-destructive, open-world operation. The description adds useful context that indexing is kicked off as a side effect, but says nothing about indexing latency, async completion, permissions, or failure behavior.

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 short sentences, no filler, with the action and its effect front-loaded before the input note. Every clause earns its place.

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 simple 3-parameter tool with full schema coverage and annotations covering the safety profile, the description covers the essentials. The only gap is what happens after indexing starts (status, return value), though no output schema exists to lean on.

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 coverage is 100%, so the parameter docs already carry the load and the baseline is 3. The phrase 'a single page or site URL' adds a small amount of meaning about acceptable URL scope beyond the schema's terse 'The website URL to index.'

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 and resource ('Add a website knowledge source by URL') and adds the operational effect ('start indexing it'), which separates it from read-oriented siblings like list_sources. It doesn't explicitly name recrawl_source, so the distinction from that nearest sibling is left implicit.

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?

'Add ... by URL' combined with the existing recrawl_source sibling implies this is for new sources rather than refreshing existing ones, but the description never says when to use this instead of recrawl_source. Usage is inferable rather than stated.

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