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

Annotations already declare readOnly/idempotent/openWorld=false, so safety is covered. The description adds non-trivial behavioral scope: it searches BOTH built-in and custom exercises, and returns each result's `slug` plus the user's own `note` (or null). That said, return details overlap with the output schema, keeping it just below a 5.

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, front-loaded with the when-to-use trigger, then the search mechanics and return shape. Every clause adds information and nothing is redundant.

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?

With an output schema present, return values need not be fully restated, and the description appropriately focuses on usage and filtering. The one gap is the unexplained `limit` parameter, which slightly under-informs the call for a moderate-complexity tool.

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 parameter meaning. It explains `search` (a name, any app language), `muscle_group` and `equipment`, and even adds the 'any app language' nuance, but leaves the `limit` parameter entirely undocumented in both schema and description.

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 (searches/Searches) and resource (built-in and custom exercises) and explicitly frames the tool's role as supplying an exercise's `slug` for other Reps tools. An agent can distinguish it from siblings like add_custom_exercise or get_exercise_progression 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?

Gives a clear triggering condition: 'Use this when you need an exercise's slug for another Reps tool, or the user asks which exercises exist for a muscle group or equipment.' It does not name an alternative tool or state when NOT to use it, so it stops short of the exclusionary guidance a 5 requires.

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