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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds that the mark is 'live' (explaining the idempotentHint=false) and denominated in dollars, which is useful context, but it says nothing about update frequency, rate limits, or behavior when a ticker is unknown.

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 sentences, no filler, with the core meaning front-loaded and the input-source hint trailing. Every clause earns its place.

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 single-parameter read tool with an output schema and full annotation coverage, the description supplies what/unit/input-source and leaves return formatting to the output schema. Only edge-case behavior (invalid or expired ticker) is unaddressed.

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 100% and the schema already supplies the KXBTCPERP example, so the baseline is 3. The description goes beyond the schema by telling the agent where valid ticker values originate (list_perps), which is actionable provenance the schema does not provide.

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 resource (the live settlement mark) for a specific instrument class (Kalshi perpetual ticker) and gives the unit (dollars), which distinguishes it from get_perp_history and list_perps. It stops short of explicitly contrasting itself with the history sibling, but the purpose is unmistakable.

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 second sentence, 'Tickers come from list_perps,' is real routing guidance for obtaining the required input and points at a sibling tool. However there is no statement of when to prefer this over get_perp_history or get_market, and no exclusions or preconditions.

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