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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety and live-fetch profile is covered. The description adds a genuinely useful non-obvious fact — that previously saved lists are not modified by the re-read — but says nothing about failure modes, caching, or whether the preview reflects the live page at call time.

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, front-loaded sentences with no filler; the core action comes first. The trailing clause 'Earlier lists stay unchanged' is terse to the point of ambiguity but does earn its place as a side-effect note.

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 output schema, the description should carry the return-value burden, and 'previews its rows' only loosely signals that rows are returned without saying how many, whether they are paginated, or how they differ from list_web_sources output. For a simple single-parameter read tool it is close to adequate but leaves the return shape under-specified.

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% for the single required parameter source_id, and the description never mentions it, so it fails to compensate for the coverage gap. An agent must infer that source_id refers to a saved web source identifier, likely from list_web_sources or save_web_source_list output.

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 concrete verb and resource: it re-reads a saved web source's page and previews its rows. However, with siblings like get_web_source and get_web_source_preview present, it never clarifies how 'preview' here differs from those, so an agent cannot confidently separate the three without opening the schemas.

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?

There is no explicit when-to-use guidance and no mention of the near-identical siblings (get_web_source, get_web_source_preview, save_web_source_list, teach_web_source). The sentence 'Earlier lists stay unchanged' hints at a re-fetch scenario but is a behavioral note rather than a selection rule.

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