media_detect_black

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

Annotations already declare readOnlyHint=true, so the read-only nature is disclosed. The description adds implementation context ('Runs ffmpeg's blackdetect filter') and intent, which provides value beyond the annotation. No contradictions exist.

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 highly concise: two sentences with a clear front-loaded purpose statement followed by relevant context. Every sentence contributes value without redundancy or filler.

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?

The tool is relatively simple, and the output schema covers return values. The description covers purpose, use cases, and underlying implementation, which is sufficient for an agent to select and invoke the tool. Minor gaps like explicit file prerequisite are not critical given the obvious input definition.

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 100%, so the schema already documents all parameters (file_path, threshold, min_duration_sec) with their defaults and meanings. The description adds no additional parameter semantics; it relies on the schema, which is acceptable at the baseline.

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 specific action ('Detect black-frame spans') with a clear resource and scope (leader, slate gaps, missing media). It is easily distinguishable from siblings like media_detect_silence and media_probe, which focus on different detection tasks.

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 use cases ('locating a slate, 2-pop leader, or accidental black holes before conform'), indicating when to use the tool. It does not explicitly name alternatives or exclusions, but the context is sufficiently clear to guide appropriate usage.

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