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

Annotations already declare the safe read-only, idempotent profile. The description adds genuinely new behavioral context: the data comes from TWSE/TPEx and is published daily, which tells an agent how fresh or stale the returned ratios may be. It does not say what happens on unresolvable or delisted symbols, keeping it below a 5.

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 what is returned and where it comes from, followed by illustrative queries. The example questions are useful for retrieval matching but slightly redundant with the preceding metric list.

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?

With no output schema, the description carries the burden of stating return values, and it does list the three ratios plus the source and refresh cadence. It leaves the response shape (per-symbol vs. aggregate) unspecified, which is a minor gap for a single-parameter lookup tool.

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 100%, and the schema itself already documents comma-separated symbols, name/code resolution and the 20-per-call limit. The description adds no syntax or format detail beyond what the schema provides, so the baseline 3 applies.

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 names three concrete metrics (P/E, dividend yield, P/B) and scopes them to Taiwan-listed shares sourced from TWSE/TPEx, which clearly distinguishes it from taiwan_stock_quote (price) or taiwan_company_profile. It stops short of naming a sibling tool, so it is clear but not explicitly differentiated.

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 sample questions ("what is TSMC trading at in P/E terms", "dividend yield on 2412") imply when the tool is useful, but there is no explicit guidance on when to prefer it over taiwan_stock_quote or taiwan_company_profile, and no exclusions or prerequisites.

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