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

Annotations are all false and uninformative, so the description carries the behavioral disclosure burden. It explains that the tool modifies the chart being built and that the result is not accessible until chart_link is called, which is a useful behavioral caveat. A simple setter does not require extensive side-effect documentation.

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, no filler, with the key action first and the required follow-up second. Every sentence earns its place.

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 state-changing tool, the description covers what is changed, gives valid example inputs, and states the necessary follow-up call. Nothing essential is missing for an agent to invoke it correctly.

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?

The schema only defines timeframe as a string with no enum or format, so the description's examples ('15m, 1h, 4h, 1d') add essential meaning. It does not provide a complete allowed-values list, but the examples are enough for common usage.

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 uses a specific verb ('Change') with a precise resource ('the chart timeframe') and provides concrete examples ('15m, 1h, 4h, 1d'). It clearly differentiates the tool from siblings like chart_set_instrument and chart_set_type.

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?

The description places the tool in the chart-building workflow and explicitly instructs calling chart_link afterward so the person can open the chart. It does not enumerate alternatives, but the purpose is distinctive enough that an agent can infer when this tool is appropriate.

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