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

With no annotations, the description carries the full burden, and it does disclose that shortened sessions are returned with half_day and early_close_time fields plus the 'start defaults to today' behavior. It does not say whether 'end' is inclusive, whether results are sorted, how many entries are returned, or what happens with an unknown MIC.

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?

A single dense sentence with the market identifier and the default behavior front-loaded; nothing is wasted. The parenthetical list of return fields is slightly awkward but earns its place by describing output.

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 simple read-only lookup with no output schema, the description covers the core semantics and one return field group, which is close to sufficient. However, the undocumented 'end' parameter and the absence of any note on timezone or range inclusivity leave real gaps for an agent constructing a query.

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%, so the description must compensate: it explains the 'market' format (ISO 10383 MIC, e.g. XNYS) and the default for 'start'. The 'end' parameter is never mentioned, so a third of the parameters remain completely undocumented.

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 and resource ('Exchange trading holidays for a market') and pins the market identifier to ISO 10383 MIC with an example (XNYS). The scope ('days the exchange is closed for trading') implicitly separates it from bank_holidays or settlement_holidays, but never names those siblings explicitly.

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 is only implied by the phrase 'days the exchange is closed for trading'; there is no explicit statement of when to pick this over bank_holidays, settlement_holidays, or get_holidays. No prerequisites or exclusions are given.

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