Validate ticker symbol

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

The description goes well beyond the readOnlyHint annotation by detailing exact matching behavior ('case-insensitive... "areit" and "AREIT" both resolve'), unknown-symbol handling ('valid: false with null fields, not an error'), and caching ('Cached after the first lookup and refreshed daily'). These are non-obvious behaviors an agent needs to know.

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 yet information-dense, using short paragraphs and a front-loaded purpose statement. Every sentence adds value—purpose, cost hint, usage alternative, return behavior, matching rules, and caching—with no repetition or 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?

Despite having an output schema, the description still explains the key return components (valid flag, company name/id, null fields) and error behavior. It also covers caching, performance, and provides differentiation from the most relevant sibling, making it complete for decision-making.

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 0% schema coverage, the description compensates by defining the sole parameter ('ticker symbol') and illustrating semantics with case-sensitivity examples. It does not provide exhaustive format restrictions, but the examples and matching rules give sufficient meaning for correct use.

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 clear, specific purpose: 'Check whether a ticker symbol is a real PSE-listed company.' It uses a strong verb ('check') and explicitly differentiates from the sibling tool search_companies by contrasting the return type (valid true/false vs. ranked list of near-matches).

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?

Usage guidance is explicit: 'Use this — NOT search_companies — when you only need to know whether a symbol is valid before calling another tool, or to confirm a symbol a user typed.' It also names the alternative and explains why this tool is preferred, giving clear decision criteria.

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