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

No annotations are provided, so the description carries the full burden. It voluntarily discloses the cost (1 credit per call), which is real added value, but says nothing about error handling for malformed timecodes, what the response contains, or drop-frame edge cases. For a stateless read-only calculator the risk is low, so this is a moderate gap rather than a severe one.

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 plus a cost line, all front-loaded: capability first, supported frame rates second, pricing last. No filler and every clause 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?

There is no output schema, so the description should ideally say what comes back for each mode; it does not, and the frame-rate list is incomplete relative to the enum. Still, for a multi-mode maths tool it conveys enough to call correctly, so the shortfall is minor rather than disqualifying.

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 40% (only timecode and add_timecode are documented), so the description must compensate and it only partly does: it explains the modes but not which parameter combinations trigger them, nor the relationship between frames/seconds/timecode as alternate inputs. It also lists only 5 of the 8 enum frame rates, omitting 50, 59.94 and 60.

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?

States specific verbs and resources: convert timecode/frames/seconds, add or subtract timecodes, compute durations, at a given frame rate. This is unmistakably distinct from neighbours like tempo_calculator, ab_test_calc, or currency_convert, so an agent can select it without opening the schema.

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 enumerates the operations (convert, add/subtract, duration) but never says how to select among them, and with 0 required parameters that selection is entirely carried by which inputs you supply. No alternatives or when-not-to-use guidance is given, though few siblings overlap this domain.

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