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

Annotations cover the safety profile (readOnlyHint=true, openWorldHint=true), so the bar is lower. The description adds real value by disclosing the input constraint (live-page URLs unsupported) and what is returned (metadata plus body paragraphs). It stops short of noting rate limits or partial-body behavior, but the transparency is good.

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 tight sentences, zero filler, and the core purpose is front-loaded ahead of the routing guidance. 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 single-parameter read tool with an output schema, the description covers what it does, the input constraint, and how to reach it from sibling tools. Return values are carried by the output schema, so nothing essential 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?

Only one parameter, and schema coverage is 100% (the schema already describes it as a 'Canonical BBC News article URL'). The description reinforces the canonical requirement and adds the live-URL exclusion, but this is more usage guidance than new parameter semantics. Baseline 3 is appropriate.

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 (public BBC News article metadata and body paragraphs) plus the input source (canonical url). It explicitly differentiates itself from bbc_search/bbc_headlines (finding stories) and bbc_live (live page snapshot), so an agent can route correctly without opening 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?

Gives an explicit when-not (live-page URLs are not supported) and names concrete alternatives with the condition that selects each (bbc_search/bbc_headlines to find a story, bbc_live for point-in-time live text). Nothing is left to inference.

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