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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful constraint that results are scoped to 'one public section' and that the section arg is validated against another tool, but says nothing about result volume, pagination, or freshness beyond the word 'Current'.

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?

A single clause pair with zero padding, and the scope constraint is front-loaded before the prerequisite.

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 one-parameter listing tool with an output schema and read-only annotations, the essentials are present: purpose, scope, and where to get valid sections. Return shape and result count are correctly left to the output schema.

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 slug list lives in the schema, so baseline would be 3. The description goes slightly beyond it by tying the parameter to cbc_sections as the authoritative source, telling the agent not to invent section values.

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 concrete verb+resource: 'Current CBC News headlines for one public section.' An agent can distinguish it from cbc_article (single article) and cbc_news, though the description does not explicitly name those siblings the way a 5 would.

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 a real prerequisite rather than just context: the section value 'must come from cbc_sections,' which routes the agent to the sibling tool first. It stops short of stating when to prefer cbc_news or how many calls to make for multiple sections, so no explicit exclusions.

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