read_muscle_balance

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

Annotations already declare a safe read (readOnly, non-destructive), so the bar is low, and the description goes well beyond it: it discloses the exact weighting scheme (target muscle 1/set, secondary 0.4), the level 1-4 relative ranking, the default window inclusive of today, and a data-source caveat that the exercise dataset's muscles can differ from the app's own map. This is rich, non-obvious behavioral context.

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?

A single dense sentence, front-loaded with the purpose and then the computation, ranking, defaults and caveat. Every clause earns its place, though the run-on construction is mildly harder to scan than a split sentence would be.

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 the return shape, and it does: ranked muscles, level 1-4, default window, and the not-trained muscles. Nothing an agent needs to call and interpret this tool is missing.

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 coverage is 100%, so the from/to date format and local-calendar-day semantics are already documented, giving a baseline of 3. The description adds a genuine default ('default the last 7 days, today included') that the schema does not express, pushing it above baseline.

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 (read/report) and a narrowly defined resource (muscle balance per muscle over a date range), and the domain is distinct enough that it can be told apart from siblings like read_training_summary or read_exercise_history at a glance. The 'completed work sets per muscle' framing pins down exactly what is being computed.

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 the clear resource definition and the default window ('default the last 7 days, today included'), but the description never states when to reach for this rather than read_training_summary or read_exercise_history, nor any exclusions. Adequate but leaves routing to inference.

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