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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the mutation/safety profile is covered. The description adds only that it edits 'the chart you are building' and the follow-up workflow, but discloses nothing about failure on invalid input, persistence, or state effects. With annotations carrying the safety burden, a 3 is appropriate.

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?

Two sentences, front-loaded with the action, no filler. The second sentence is slightly dense with two downstream tool options packed into one clause, but overall it is tight and earns its place.

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 single-parameter setter with no output schema and full annotation coverage, the description supplies purpose, value format, and post-step workflow. Remaining gaps (invalid-value handling, interaction with other chart state) are minor for a tool of this complexity.

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% (the 'timeframe' string is undocumented), so the description must compensate, and it does with format examples (15m, 1h, 4h, 1d). It doesn't enumerate the full accepted set or note case/edge behavior, but it materially teaches the expected value shape beyond the bare schema.

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 (Change) and resource (chart timeframe) and immediately gives concrete format examples (15m, 1h, 4h, 1d). The 'timeframe' resource is unique among the chart_* siblings (set_instrument, set_type), so an agent can distinguish it without opening a 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 real workflow guidance: 'Changes the chart you are building; finish with chart_link, or analysis_prepare for a sharing draft.' This names downstream alternatives and the condition for each (sharing draft needing human review). It lacks any explicit when-not-to-use or prerequisite, so it falls short of a 5.

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