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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavior details: it removes prose preambles and repairs malformed control characters, and explains the consequences it prevents (JSONDecodeErrors, session poisoning). This goes beyond the annotation information.

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 concise sentences, with the first sentence front-loading the usage context and the second describing the behavior. No filler or redundant information.

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 tool with one required parameter and no output schema. The description covers when and what clearly. It does not explicitly state the return value or the role of api_key_id, but these are reasonably inferable from the tool's purpose and schema descriptions, making it slightly incomplete but adequate.

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%, so the baseline is 3. The description adds no parameter-specific details, but the schema already provides clear descriptions for both raw_string and api_key_id, so no additional burden falls on the description.

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 tool's purpose: sanitize JSON output by removing prose and repairing control characters before saving. It differentiates itself from siblings by focusing on the pre-save use case, though it does not explicitly contrast with repair_json or validate_json by name.

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 explicitly says when to use the tool: 'before saving any JSON data to session history or state files.' It provides a clear context and rationale, but it doesn't mention when not to use it or alternative tools for validation/repair in other scenarios.

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