Add custom chart series

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

Annotations indicate destructiveHint=false, readOnlyHint=false, so it's a mutation but not destructive. The description says 'Add or replace' which implies it updates existing series. However, it doesn't clarify the effect on existing data, authorization needs, or whether it's reversible. With annotations already flags, the description adds minimal extra behavioral detail.

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?

Description is a single, concise sentence that states the action, resource, and supported types. No redundancy or fluff.

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?

Given the tool has 8 parameters (3 required), a rich schema, and an output schema absent, the description is reasonably complete. It lists supported series types and clarifies scope. Although it doesn't explain return values or error behavior, the schema is self-explanatory and the tool is focused. It could mention behavior for replacement or id usage, but it's adequate.

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 provides full parameter definitions with enums and defaults frequenciesing. The description adds context about supported series types (price overlays, CVD panes, etc.) which hints at how pane/kind might relate. But it doesn't explain parameter interplay or data structure beyond what schema shows. Schema coverage is 0% per signal, but the schema itself is fairly descriptive with types and enums, so the description adds marginal value.

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 clearly states the tool's purpose: 'Add or replace a time-aligned line or histogram series.' It specifies the action (add/replace), the resource (chart series), and the allowed types (line/histogram). The mention of supported series types (price overlays, CVD panes, etc.) adds context and distinguishes it from siblings like chart_add_indicator, which would add indicators rather than raw data series.

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 gives context on what kinds of series are appropriate (price overlays, CVD panes, expected paths, etc.), which helps the agent decide when to use this tool vs. alternatives like adding indicators or levels. However, it doesn't explicitly state when not to use it or mention sibling tools like chart_add_indicator or chart_set_data for comparison.

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