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

Beyond the read-only/idempotent annotations, the description explains that the widget reuses captured source numbers and selection, does not fetch or calculate new data, and requires a new read once evidence expires. These are meaningful behavioral constraints an agent would otherwise have to discover by trial.

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 front-loaded with the core action and prerequisite, and every sentence contributes either a usage condition or a behavioral boundary. It is slightly verbose with stacked negations and could be tightened, but it is not padded.

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?

Given the single required parameter, full schema coverage, annotations, and an output schema, the description supplies everything else the agent needs: when to use it, what it is not, prerequisite evidence, and expiry behavior. No essential context is missing 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?

With 100% schema description coverage, the schema already defines the required evidence_id precisely. The description adds useful context about the source tool and evidence expiry, but mostly reinforces what the schema states rather than adding new parameter-level syntax or format details.

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: 'Display a focused positioning chart widget', and names the content domain (long/short account ratios or tracked-position observations). It also explicitly distinguishes herself from sibling tools by stating it is 'Not a data fetch, calculation, navigation hub or replacement for the assistant's interpretation.'

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?

It states the exact prerequisite ('after evidence from research_read_series is available') and the selection condition ('Use only when a visual helps answer the question'). It also names exclusions and the recovery path for expired evidence ('expired evidence requires an explicit new read'), leaving little to inference.

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