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

Annotations already declare readOnlyHint/idempotentHint/openWorldHint, and the description adds genuinely new context: the payload is intentionally schema-free to save context on limited clients, and through Royally it is read-only and runs immediately. The only shortfall is that it doesn't say whether the result list is capped or paginated when many tools match.

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?

Front-loaded with the purpose and return shape, then the workflow. Slight redundancy at the end — the Royally sentence repeats the discover/get_tool_info/execute_tool chain already stated, and the parenthetical site URL duplicates the schema's site_id description.

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 no output schema, the description substitutes by describing the returned index fields and what is deliberately omitted. Combined with the three-tool workflow, an agent has enough to use it correctly; only result-size/pagination behavior is unaddressed.

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 every filter, including examples and the capability inference rule. The description restates the four filter dimensions but adds no syntax or semantics beyond the schema, 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?

The first sentence gives a specific verb (list) plus the resource (Royal MCP tools) and enumerates the four filter axes. It explicitly states the return shape (compact index, name/description/metadata, no inputSchema), so an agent knows exactly what it gets back versus what sibling tools return.

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?

It names the exact workflow — discover, then get_tool_info for inputs, then execute_tool to dispatch — and calls out the compact profile condition under which this tool is the right choice. It also explains its relation to the default site listing ("Royally lists each site's most-used tools; use this to find any other tool"), so the when-to-use boundary is explicit.

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