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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and network profile is covered. The description adds modest context ("current" implying freshness, "public section" implying non-public sections are out of scope), but does not describe volume, pagination, or ordering. With annotations and an output schema carrying much of the load, a 3 is appropriate.

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, purpose front-loaded, followed by the input sourcing and the sibling routing. No filler; every clause carries actionable information.

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?

Output schema exists so return values need not be described, annotations cover the safety profile, the single parameter is fully documented in the schema with values, and the description handles sibling disambiguation. Nothing an agent needs to call this 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 section property already enumerates 28 valid slugs. The description goes beyond the schema by telling the agent the authoritative source for those values (cbr_sections), which is real added meaning for a parameter whose valid set is opaque.

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) plus resource (current CBR story cards) and scope (one public section). It explicitly distinguishes itself from siblings cbr_news (general feed) and cbr_article (a single story's body), so an agent can differentiate without opening any schema.

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: says to source the section value from cbr_sections, and names the alternatives (cbr_news for the general feed, cbr_article for one story's body) with the conditions that select them. When-to-use and when-to-use-something-else are both covered.

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