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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed world), so the bar is lower. The description adds real value beyond them: it scopes the content to general fitness information ('never diagnoses pain or injury') and imposes an output-handling rule ('never show the user rows, columns, codes, raw records or links').

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 core purpose is front-loaded in the first clause, with return contents then constraints in descending priority. The two constraint sentences are dense but each carries a distinct rule; the 'Figures are for building finished answers only' phrasing is slightly awkward but 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 carries the burden of describing returns, and it does so by listing the content categories an agent will get. Combined with annotations and a fully documented one-parameter schema, an agent has enough to call this correctly; only formatting/structure of the returned record is unspecified.

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% and the single parameter already documents its origin in search_exercises. The description's 'by slug' restates the schema rather than adding format, length, or resolution guidance, so the baseline 3 applies.

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 a specific verb and resource ('One exercise by slug') and enumerates the returned content (muscles, equipment, setup, execution, breathing, ROM, common errors, alternatives). This clearly separates it from the sibling search_exercises, which returns many matches rather than one detailed record.

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 is implied: 'by slug' plus the schema's note that the slug comes from search_exercises signals the lookup pattern. However, the description never explicitly states when to pick this tool over search_exercises or search_public_content, and it gives no preconditions beyond the safety caveat.

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