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

Annotations already declare readOnly/openWorld/non-destructive, and the description adds substantial context beyond them: 15m charts auto-adjust longer periods to 5d and cap at 350 bars, bollinger overlays SMA20 ± 2σ and returns band values, and clients lacking interactive app support can fall back to the result's `summary` field. These are real behavioral traits (limits, fallbacks, output side-effects) that an agent cannot get from structured fields.

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 paragraph that front-loads the core action before moving to symbol types, parameters, and fallbacks. Every clause carries information, though the run-on format with inline value lists could be structured more scannably.

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 4-parameter tool with no output schema and no schema descriptions, the definition covers the important ground: what is rendered, symbol formats, parameter values, chart limits, and what the result contains. It is close to complete, with only the period/interval value inconsistency and lack of sibling routing as notable gaps.

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?

With 0% schema description coverage, the description carries the full burden and mostly succeeds: it enumerates period values, interval values, explains the bollinger flag and its effect, and gives symbol format examples. One gap is that `5d` is presented as valid for 15m charts but is absent from the stated period list, leaving a minor inconsistency for the agent to resolve.

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 names a specific verb and resource ('Render an interactive candlestick chart for a symbol') and clarifies accepted symbol types (crypto pairs, stocks, Yahoo Finance symbols). It is clearly a visualization tool, distinguishable in kind from scanner/analysis siblings, though it never explicitly names an alternative such as yahoo_price or backtest_chart.

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 through parameter context (period/interval combos, when 15m is appropriate), but there is no explicit 'use this when' guidance or routing against siblings that also surface price data (yahoo_price, stock_prices). An agent must infer that this is the charting option rather than a data-retrieval one.

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