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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the scoping constraint (only 5 preview systems available via this MCP) and the 'focused reading for ONE specific system' behavior, which is useful. However, it does not disclose what a 'focused reading' contains, whether lat/lon/timezone are required for accuracy, or any rate limits or error behavior.

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?

The description is two sentences and front-loads the core purpose ('focused reading for ONE specific divination system') before the scoping detail. It is concise and every sentence earns its place, though it could be slightly more structured by separating the scope note.

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 has 10 parameters, no output schema, and only 10% schema description coverage, the description is not fully complete. It clarifies the system scope and the 'one system' behavior, but it does not explain the role of lat/lon/timezone, the meaning of a 'focused reading', or how the response is structured. The sibling list_26_systems is referenced in the schema, which helps, but the description itself could do more.

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 only 10%, so the description must compensate for the 10 parameters. The description mentions 'ONE specific divination system' and the 5 preview systems, which maps to the 'system' parameter, but it does not explain the meaning of year/month/day/hour/minute/lat/lon/timezone/lang beyond what the schema already provides. The schema itself only describes 'system' as 'System slug — see list_26_systems', so the description adds minimal value for the other parameters.

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 states a specific verb ('Get') and resource ('a focused reading for ONE specific divination system from the 26'), and it distinguishes itself by naming the 5 preview systems covered by this MCP versus the other 21 on mythsensus.com. It is clear what the tool does, though it does not explicitly name sibling tools like get_system_rules or list_26_systems to differentiate further.

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?

The description gives clear context: use this for one specific system among the 26, and it explicitly notes that only 5 preview systems are covered here while the other 21 are on mythsensus.com. This implies when to use this tool versus going to the website, but it does not explicitly state when to use alternatives like get_system_rules or list_26_systems.

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