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

The description discloses that this tool mutates the chart being built and that chart_link must be called afterward for the person to open it. This adds meaningful side-effect context beyond the annotations. It does not detail whether params are merged or fully replaced, but the mutation and linking requirement are clearly conveyed.

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?

The description is compact and well ordered: purpose first, then prerequisite steps, then sibling alternatives, then side effects. Every sentence carries distinct information and avoids redundant restatement of the tool name or schema.

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 two-parameter mutation tool with sparse annotations and no output schema, the description covers the essential context: what it does, how to obtain required inputs, what alternatives exist, and what post-condition must be satisfied. It does not describe the return value, but the tool's main purpose and invocation path are sufficiently complete.

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 0%, but the description compensates by explaining where to obtain instanceId ('call chart_state') and how to find valid parameter names/values ('use catalog_describe'). This gives the agent a concrete path to fill the two required parameters even though the params object shape is not directly specified.

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 and resource: 'Edit the parameters of an existing indicator instance.' It clearly scopes the tool to modifying an existing instance rather than creating or removing it, and explicitly distinguishes it from sibling tools like chart_remove_indicator and chart_toggle_indicator. The purpose is unambiguous and immediately actionable.

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 provides explicit workflow guidance: call chart_state first to obtain the instanceId, and use catalog_describe to learn supported parameters. It also names alternatives for other operations ('To delete use chart_remove_indicator, to hide/show use chart_toggle_indicator'), giving the agent clear routing criteria for when this tool is and is not appropriate.

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