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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context about contentVersion being an opaque change token that must not be parsed or ordered, plus a caching strategy. This goes beyond the annotations and enriches the agent's understanding of the tool's contract.

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 tight sentences: the first lists the returned re-sync signals, the second states the persistence strategy. No filler or repetition. Every phrase carries meaning, and the most important info (contentVersion handling) is front-loaded. This is an example of efficient, high-signal writing.

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 bears responsibility for explaining return values, and it does: contentVersion, hasActiveJob, apiReady, pose/animation counts, tags, favourite. It also provides the important re-fetch strategy. It doesn't explicitly state that the result is a list or cover pagination, but the limit parameter handles that. Overall, it is complete for a read-only list tool with good annotations.

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 covers 100% of parameters with descriptions (name substring filter, limit with default/max, projectId restrict). The description adds no parameter-specific detail beyond what the schema provides, so the baseline of 3 applies. It does not mention parameters at all, but the schema is fully sufficient.

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 focuses on the re-sync signals returned for characters, which clearly implies this lists characters. The tool name and title explicitly say 'List characters', and the description distinguishes it from singular get_character by emphasizing the list with change tokens. However, the description lacks an explicit verb like 'lists' or 'returns', relying on context.

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 a clear usage pattern: 'Persist contentVersion per character and re-fetch only when it changes.' This tells the agent when to call the tool and how to use it efficiently. It does not explicitly mention alternatives like get_character for single-character retrieval, but the polling guidance is strong. There's no 'when not to use' exclusion, but the context is clear.

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