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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that by disclosing the shape of the return (one-line description and URL per entry).

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, zero waste: the first states what is returned, the second states why to call it. The purpose is front-loaded and the usage note follows naturally.

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 zero-param directory tool with no output schema, the description is nearly complete: it explains what the listing contains and the intent behind calling it. A small gap is the absence of pagination or full-list-size expectations, though that is minor for a static known catalog.

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?

The tool takes zero parameters, so there is nothing for the description to document; the empty schema is self-explanatory. Baseline 4 applies for a no-argument tool.

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 (lists) and resource (every UK property calculator on realyield.co.uk), plus the return content (one-line description and URL). This clearly separates it from sibling tools like calculate_stamp_duty or search_realyield, which perform actions rather than enumerate the available tools.

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 says when to use it: 'to find the right tool for a landlord question before navigating or calculating.' That is a clear context, though it does not name the alternative (search_realyield) or state when this directory listing is unnecessary.

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