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

Annotations only declare the generic safety profile (not read-only, not destructive, not idempotent). The description adds real behavior: studyId accepts common names, omitted params fall back to defaults, and the call mutates the chart being built. It stops short of noting duplicate/repeat-add behavior, which matters given idempotentHint=false.

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?

Compact and front-loaded: the action leads, then parameter syntax, then the completion path. Every clause carries information, though the final sentence packs two alternative next steps and is slightly denser than needed.

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?

No output schema exists, but the tool returns little the agent needs to see described; the description covers the mutation, parameter sourcing, and next-step tools. The one gap is what happens on repeated adds, which is relevant given idempotentHint=false.

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 coverage is 0% and the nested params object is undocumented, but the description compensates well: studyId takes an id or a common name with concrete examples ('ema20', 'bollinger'), catalog_describe enumerates valid parameters, and missing params use defaults. The internal shape of the params object is still only discoverable elsewhere.

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?

States a specific verb and resource ('Put an indicator on the chart') and frames it as a mutation of the chart being built. Combined with the sibling names (chart_toggle_indicator, chart_update_indicator, chart_remove_indicator), an agent can tell this is the additive variant without opening any schema.

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?

Gives clear workflow routing: call catalog_describe to discover parameters, then finish with chart_link, or analysis_prepare when a sharing draft needing human review is wanted. It does not explicitly contrast with chart_toggle_indicator/chart_update_indicator, so the when-not case is left to inference.

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