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

Annotations already declare a safe read (readOnly, idempotent, closed-world), but the description adds real behavioral context: a 15-second Mux clip, up to five newest confirmed workout appearances, no separate YouTube demo, and the fact that start_seconds already includes the four-second lead-in. The 'do not claim clinical or technique certification' constraint and the video_status fallback are exactly the kind of policy disclosure annotations cannot carry.

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?

Front-loads the identity and provenance of the lookup, then moves to return contents and operating constraints. Every sentence carries information, though the video/YouTube sentences are dense output-field detail that reads slightly list-like.

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 must describe returns itself — and it does, naming equipment, the video segment, workout appearances, full_video_url and video_status. Combined with the fallback behavior and the exact-slug acquisition rule, an agent has everything needed to call it and present results honestly.

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 schema has 0% description coverage on the single slug parameter, so the description must compensate. It does so by specifying the slug is the *exact* one from search_exercises, which tells the agent where to obtain a valid value rather than inventing one, though it does not restate the lowercase-hyphen format the schema pattern enforces.

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?

Names a specific verb (get) and resource (a catalog exercise) and states the lookup key is an exact slug sourced from search_exercises. That explicitly distinguishes it from its only sibling, which is a search rather than a lookup.

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?

Routes the agent to search_exercises as the source of the slug and gives an explicit fallback branch for when video_status is unavailable. It stops short of an explicit 'do not call with a guessed name, call search_exercises first', so the boundary is strong but not fully spelled out.

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