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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds useful content about what the profile contains, but with an output schema present this is largely redundant, and it says nothing about rate limits, auth, or failure modes.

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: the fetch purpose and payload come first, the disambiguation second. No wasted words.

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 simple single-parameter read tool with an output schema and safety annotations, the description covers purpose, payload, and sibling routing. Minor gaps (no mention of pagination of recent stories or edge cases) keep it from a 5.

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 there is a single required parameter, so the schema fully documents `url`. The description reinforces that it must be the 'canonical author url' but adds no format or example beyond the schema's own description. 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 ('CTV News byline profile') and enumerates the returned fields (role, biography, photo, contact address, recent stories). It also distinguishes itself from the sibling story tools, so an agent can identify it without opening the 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 to ctvnews_headlines for story lists and ctvnews_article for a single story, giving clear context for when this tool is the right choice. It stops short of stating prerequisites or when NOT to fetch a profile, but the alternative routing is solid.

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