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

Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, and the description usefully confirms this is a mutation of "the chart you are building" plus that the indicator is preserved. However, it does not disclose how the toggle's target state is determined (the agent must infer a blind flip), which is the key behavioral question for a non-idempotent toggle.

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 short sentences with no filler; the purpose is front-loaded ahead of the workflow guidance. The clause about chart_link/analysis_prepare is slightly dense but earns its place by routing the next action.

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 single-parameter mutation tool with no output schema, the description covers purpose and next steps, but leaves two things an agent needs: the meaning of instanceId and how the hide/show state is selected. These gaps are narrow but real.

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% for the single required parameter, and the description says nothing about instanceId — whether it identifies the chart instance or the indicator instance is left entirely undefined. With only one parameter the impact is bounded, but the description does not compensate for the schema gap as it should.

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 gives a concrete verb pair and resource ("Hide or show an indicator") and immediately distinguishes the operation from removal with "without removing it", which separates it from chart_remove_indicator. It stops short of naming siblings explicitly (chart_remove_indicator, chart_update_indicator), so it is clear but not maximally differentiating.

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?

It states a use case ("useful for comparing a chart with and without something") and gives explicit follow-on workflow guidance: finish with chart_link, or analysis_prepare for a sharing draft needing human review. What's missing is guidance on the hide-vs-show decision itself, so the agent isn't told when it should hide versus show.

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