Market summary

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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds substantial context: how feeds are keyed (group labels), what each entry carries (symbol, timestamp, circular number, edge_no), and a critical limitation (PSE Edge publishes no gainers/losers/most-active data anywhere). This goes beyond the structured annotations and helps the agent interpret results and avoid misstatements.

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 first sentence is a concise summary. The second paragraph lists the feed keys and their fields, which is necessary detail given the tool's output scope. The limitation note is important and earns its place. Slightly dense but well-organized; no filler.

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 output schema exists, the description doesn't need to list return fields, but it still provides essential context: feed structure, key labels, and the data limitation. With zero parameters and a rich output description, an agent has enough to invoke the tool and interpret results without ambiguity.

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?

The input schema has zero parameters, and the description itself doesn't mention parameters, which is appropriate. With no parameters, the schema coverage is trivially 100% and the baseline is 4. The description adds no param semantics because none exist.

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 uses a specific verb ('Get') and resource ('market-wide snapshot') with concrete scope: index levels plus PSE Edge's homepage feeds. This clearly differentiates it from siblings like get_indices (indices only) and search_disclosures (disclosure search), so purpose is unambiguous.

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 clear context for when to use this tool (for a market-wide snapshot) and includes an important behavioral instruction: if asked for gainers/losers, explicitly state PSE Edge doesn't publish them rather than implying missing data. It doesn't explicitly name alternatives or exclusions, but the context is enough for an agent to select this tool appropriately.

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