pi_capabilities

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

Annotations already mark this as a safe, read-only operation. The description adds behavioral context by noting that downstream tools fall back automatically when an optional process is missing, which informs an agent about the operational impact of a missing capability.

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 sentences with no filler; the core purpose is front-loaded and the fallback behavior is a single useful addendum. Every sentence 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?

For a parameterless capability-discovery tool, the description tells the agent what will be reported (which processes/scripts exist) and the fallback implication. It does not describe a return format, but no output schema exists and the tool's complexity is low, so this is a minor gap.

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?

The tool takes zero parameters and schema coverage is 100%, so there is no parameter meaning for the description to add. The baseline of 4 applies because no parameter information is needed.

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 states a clear introspective purpose: enumerating which optional PixInsight processes/scripts exist, with concrete examples (BlurXTerminator, NoiseXTerminator, etc.). It distinguishes itself from process-running siblings by focusing on existence rather than execution, though it does not explicitly name an alternative.

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?

Usage context is implied: call this to discover which optional processes are available before relying on them. The fallback note ('Tools fall back automatically when something is missing') provides a reason to check, but no explicit when-to-use/when-not-to-use guidance or named alternatives is given.

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