Charlie: explain this

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description adds limited new behavioral context. It does disclose that the output includes evidence and a fix, but does not elaborate on side effects, authentication needs, or rate limits.

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 a single, clear sentence that is front-loaded with the key purpose. It is concise with no redundant information, though it could be slightly more structured (e.g., listing evidence and fix explicitly).

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 presence of an output schema and annotations, the description is adequate for the core function but lacks explanation for all parameters. It does not describe the output in detail (relying on output schema) and does not cover the optional parameters, leaving some completeness gaps.

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 explains that finding_id is a 'toil id', but does not clarify the meaning or usage of 'repo' and 'online' parameters. The description adds value only for one of three 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 clearly states the tool's action ('Explain why a specific finding is real debt'), the resource (a finding by toil id), and what the output includes (evidence and a fix). It distinguishes this from siblings like charlie_scan_toil (which scans) and charlie_summary (which provides summary).

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 implies use when you need an explanation for a specific finding, but it does not explicitly state when to use this tool versus alternatives (e.g., charlie_triage) or when not to use it. No exclusions or prerequisites are mentioned.

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