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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutating-but-non-destructive profile is covered. The description adds one genuinely useful behavioral detail: that equipment 'plate'/'smith' makes the base weight derive from the change_settings baseWeight value. It does not say whether the exercise persists permanently, what happens if a name already exists, or what is returned on success.

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?

It is a single compact sentence, but the second clause is a run-on ('gives it a sled or bar its base weight is counted from') that is grammatically tangled and slows parsing. The core creation statement is front-loaded, which is good, but the equipment aside is dense and ambiguous.

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?

For a creation tool with four parameters, 0% schema coverage, and no output schema, the description is thin. It omits the meaning of the required 'kind' enum, the format for 'muscles', duplicate-name behavior, and any indication of the return value after creation.

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 all parameter meaning, and it only partially does. It explains two equipment enum values ('plate', 'smith') but leaves the other seven equipment values and all six 'kind' enum values ('weight_reps', 'bodyweight_reps', etc.) unexplained, and gives no format for the 'muscles' array items.

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?

The description states a concrete verb and resource: 'Makes a custom exercise' plus the fields it accepts (name, kind, muscles). It implicitly distinguishes from trainrec_list_exercises by saying the exercise is 'custom', though it never names that sibling directly.

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 only implied by the word 'custom' – the agent can infer this is for creating a new exercise rather than listing existing ones. There is no explicit 'use this when...' guidance, no mention of checking duplicates first, and the only cross-reference (change_settings for baseWeight) is about downstream effects rather than when to pick this tool.

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