Get one castle in full

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

Describes exactly what data is returned (coordinates, founding year, fame rank, photo, Wikipedia link, readership signals). No annotations exist, so description carries full burden. It lacks mention of error behavior or rate limits but is thorough for a read tool.

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, 55 words. Front-loads the action and resource, then provides a fallback hint. Every sentence is necessary and efficient.

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?

Given the tool's simplicity (1 param, no output schema, no annotations), the description covers the key aspects: how to call it, what it returns, and when to use alternatives. Minor omissions like exact output structure are acceptable for a straightforward get operation.

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?

Input schema already covers the parameter with high coverage (100%), so baseline is 3. The description adds value by emphasizing slug preference and suggesting search_castles if unsure, which helps the agent select the correct input format.

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 description clearly states 'Fetch one landmark’s full record' using a slug or exact name, and lists the returned fields. It immediately distinguishes from sibling tools like search_castles by implying this is the full record retrieval, not a search.

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 tells when NOT to use ('Unsure of the slug?') and directs to the correct alternative ('Call search_castles first'). This provides clear guidance on when to use this tool versus its sibling.

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