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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds real value beyond that: the search spans built-in AND custom exercises, filters combine, and results include the user's own note (or null). It does not mention whether `limit` truncates results or what the default ordering is.

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?

Three tight sentences, front-loaded with the usage trigger, then the search mechanism, then the return shape. No restatement of the name 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?

An output schema exists, so return values need not be spelled out, yet the description still summarizes the slug + note shape usefully. The only real hole is `limit` and result-ordering behavior for a tool with zero schema parameter documentation.

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 0%, so the description must carry the parameter burden. It explains `search` (name, any app language), `muscle_group` and `equipment`, which is genuinely useful, but `limit` is never explained and it is unclear whether multiple filters are ANDed or whether all parameters are optional.

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 ('searches built-in and custom exercises') plus the exact scope of the data. It also names the downstream reason for calling it (obtaining a `slug` for another Reps tool), which distinguishes it cleanly from siblings like get_exercise_progression or set_exercise_note.

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?

Gives two concrete triggering conditions: needing a slug for another tool, or the user asking which exercises exist for a muscle group/equipment. That is clear positive guidance, but it does not state exclusions or name the sibling to use instead when the user wants history, records, or notes rather than the library itself.

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