market_status

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds value beyond that by disclosing what the response contains — Tehran time, session hours, bourse state, and totals — which matters because there is no output schema. It stops short of stating data freshness or whether the 'totals' are intraday or end-of-session figures.

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 short clauses: a front-loaded question that states the purpose, then a compact enumeration of returned fields, plus the Persian name for local users. No filler. The field list is slightly telegraphic ('bourse state and totals') and would read better with a connector, but nothing is wasted.

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 zero parameters, no output schema, and a simple read-only nature, the definition supplies nearly everything needed: the timezone framing, the session-hours concept, and the shape of the returned state. The only gap is that it does not say how fresh the status is or whether it reflects pre-market/auction phases, which for a market-clock tool is a modest omission rather than a blocking one.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a parameterless tool is 4. The description correctly implies the caller supplies no arguments — the market's state is determined server-side.

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 question — 'Is the Tehran market open right now?' — which names the resource (Tehran market) and the exact fact being reported (open/closed state). It then enumerates the payload (Tehran time, session hours, bourse state, totals), so the agent knows this is a status check rather than a data dump. It does not explicitly contrast itself with close siblings like market_overview or market_snapshot, which keeps it from a 5.

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 phrasing: an agent can infer 'call this when you need to know whether the market is currently trading.' There is no explicit when-not guidance and no mention of the alternative siblings (market_overview, market_snapshot, market_watch) that also surface market-level state. Minimum viable for a zero-parameter read tool, but routing is left to inference.

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