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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds value by disclosing what the read returns: a live schedule covering both delivery and pickup with ASAP and future slots. No pagination or market-support caveats are mentioned, keeping it just short of 5.

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 sentences, front-loaded with the core capability followed by sibling routing. Every clause earns its place with no redundancy.

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?

With an output schema present, return values need no explanation, and annotations carry the safety profile. The description covers purpose, scope, and sibling routing, leaving nothing an agent needs to 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%, with the market enum (uk, ie, fr, etc.) and required lat/long documented in the schema itself. The description adds no syntax, default, or format detail beyond that, so the baseline 3 applies.

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 and resource ('Fetch Deliveroo's live delivery and pickup schedule'), names the market scope, and explicitly differentiates from siblings by pointing to deliveroo_search and deliveroo_restaurant_menu. An agent can identify this as the scheduling tool 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?

Gives clear context (live delivery/pickup schedule including ASAP and future slots) and names the adjacent tools (deliveroo_search, deliveroo_restaurant_menu) for other tasks. It stops short of explicit when-not-to-use or prerequisite conditions, but the workflow routing is clear.

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