Read one fantasy entity card

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so safety profile is clear. The description adds that the tool also returns 'directly related cards', which is behavioral context beyond annotations. No contradictions. Could be improved by mentioning whether results are paginated or what happens on missing key.

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?

Single sentence, no wasted words. Front-loaded with action 'Reads' and resource. Structure is optimal for quick scanning.

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 one parameter, no output schema, and annotations present, the description is minimally adequate. It states the tool reads an entity card and related cards, but omits details like what 'directly related cards' means, error behavior, or data count limits. Given the complexity (related cards), the description feels slightly incomplete.

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 0%, so the description must compensate. It mentions 'by stable key' but does not explain what a 'stable key' is, its format, or constraints (beyond schema's type and length). No examples or clarification of how the key relates to the entity. The description adds minimal semantic value over the raw schema.

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 the verb 'reads' and the resource 'one canonical fantasy entity card', and mentions it also returns 'directly related cards'. This distinguishes it from siblings like search_fantasy_catalog (search) and trace_fantasy_relations (tracing relations). However, it does not explicitly clarify the role of the 'key' parameter beyond 'stable key'.

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?

No guidance on when to use this tool versus alternatives. The description does not mention any prerequisites, when not to use it, or how it compares to sibling tools like read_web_source or search_fantasy_catalog. The agent is left to infer usage from context.

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