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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral value by naming the payload shape (metadata, section, body paragraphs) and the input rejection rule for photo-gallery URLs. It stops short of noting any rate limits, paywall/truncation behavior, or how galleries are surfaced.

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 compact sentences: the capability and its constraint come first, the discovery alternative second. No filler, no restating of the tool name.

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?

An output schema exists, so return values need not be explained, yet the description still summarizes them. For a one-parameter read-only tool with annotations covering the safety profile, nothing an agent needs in order to call it correctly is missing.

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% and the single `url` parameter is documented, so the baseline is 3. The description adds a validity constraint not present in the schema — only canonical article URLs are accepted and photo-gallery URLs are rejected — which meaningfully guides parameter construction.

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 (fetch) and resource (Birmingham Mail article), and enumerates exactly what is returned: metadata, section, and body paragraphs. This distinguishes it from the sibling headlines/news/author/sections tools, which do not return body content.

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?

Explicitly routes the agent to birminghammail_headlines or birminghammail_news for story discovery and states a rejection condition (photo-gallery URLs). Clear context for when to use it, though it gives no exclusions or guidance about the read-only vs. other article-related operations.

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