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 description doesn't carry the burden for safety disclosure. It adds the fact that results include effects and that filtering is possible, but no deeper behavioral context like pagination or return format. No contradiction with annotations.

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 concise sentences with no redundancy. The purpose is front-loaded, and the optional filter is mentioned efficiently. Every word earns its place.

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?

This is a simple listing tool with one optional parameter. The description covers what it lists, what it returns (spells with effects), and the filtering capability. Annotations handle safety, and no output schema is needed for this complexity.

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 coverage is 100% with a well-described 'search' parameter (case-insensitive substring filter). The tool description reiterates 'spell-name substring,' but does not add meaning beyond the schema. Baseline 3 is appropriate.

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 'List Harry Potter spells with their effects,' using a specific verb and resource that distinguishes it from sibling list tools like list_characters and list_students. The mention of 'effects' adds useful detail about what the tool returns.

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 provides clear context for when to use the tool (when needing spells) and mentions the optional substring filter. However, it does not explicitly exclude alternatives or name when-not conditions, but the sibling tool names make the differentiation implicit.

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