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

Annotations already carry readOnlyHint=true, destructiveHint=false, and idempotentHint=false. The description adds meaningful behavior beyond that: returns a JPEG inline plus a JSON metadata block, the api.maatsii.com url has a unique cachebuster (fresh per call, consistent with idempotentHint=false), and it warns that the printed chart title is ground truth. This is rich, non-obvious behavioral disclosure with no contradiction.

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?

Three dense sentences, each earning its place: purpose/selector, return format, and interpretation guidance. The core purpose is front-loaded, and the reading instructions are appended without redundancy. No filler or restating of what the schema already says.

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?

The tool is moderate in complexity and has an output schema, so return-value details need not be repeated. What an agent needs to invoke it correctly — required selector, return shape, and how to interpret the chart — is all present. Minor gaps (error behavior for an invalid id, meaning of 'group') are non-critical for correct invocation.

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 100%, so the schema already documents all four parameters thoroughly. The description adds concrete ticker examples (NQ_100T, BTCUSD, PLTR), clarifies the uniqueness of the cachebuster, and affirms the inline JPEG default behavior, which enriches the parameter understanding beyond the schema alone.

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 opens with a specific verb-resource pair: 'Get ONE fresh Maatsii chart by id (c1..c200) or ticker', naming exact selectors and concrete examples. It clearly distinguishes itself from the other get_* siblings by emphasizing it returns chart imagery for a single chart, not a map, concept, group, or setup.

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 context for use is explicit: you need a fresh chart image for a known id or ticker, and the description tells the agent exactly what to do with the result (vision the image, trust the printed title, read prices off the right axis). It also routes the price-reading subtask to the maatsii_reading_guide sibling. It lacks explicit 'when-not-to-use' exclusions against sibling chart tools, but the context is clear.

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