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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered structurally. The description still adds meaningful context: the profile is 'public' (no auth implied) and returns just 'one page' of article cards, which signals pagination scope. No rate limits or return-shape detail beyond that.

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 tightly written sentences: the purpose is front-loaded, then the sibling alternatives. No filler and nothing that fails to earn 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?

An output schema exists, so return values need not be described, and annotations carry the safety profile. For a simple 3-param, zero-required lookup tool, the description supplies exactly what an agent needs to select and invoke it correctly.

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 description coverage is 100%, so the schema already documents url, page, and slug with examples (e.g. martin-wolf). The description adds no parameter-level syntax or semantics, so the baseline of 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), resource (FT contributor's public profile), and additional payload (one page of recent article cards). It is clearly distinguishable from ft_article, ft_headlines, and ft_search 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: use ft_article for one story or ft_headlines to browse current headlines, clearly establishing when this tool is the wrong choice. It stops short of naming ft_search, and gives no explicit exclusion for when an author lookup should be preferred over a general search.

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