nascar_get_liveFetch live NASCAR race data: current lap, flag state, laps to go, leader, and per-vehicle running order. Returns idle fields when no race is live.
Get the live race feed: current lap, flag state, laps to go, leader and per-vehicle running order. When no race is live, fields are in an idle state (flag_state 9, race_id -1).
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | Keys to keep (comma-separated). |
Changes observed during successful MCP inspections.
v1.4.1Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"Input schema / properties / fieldsAdded value: +{
+ "description": "Keys to keep (comma-separated).",
+ "type": "string"
+}v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only/idempotent/open-world semantics, so the bar is lower, and the description still adds genuine behavioral information the annotations cannot: the idle-state sentinel values (flag_state 9, race_id -1) that let an agent distinguish 'no live race' from 'empty result'. It omits anything about refresh cadence or payload size, 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, zero filler. The primary capability and its returned fields are front-loaded, and the idle-state caveat follows as a supporting clause.
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 describing the return payload and does so by listing the key fields plus the idle-state fallback. For a zero-required-parameter, low-complexity read tool, nothing needed to invoke or interpret it correctly is missing.
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?
There is a single optional 'fields' parameter whose schema description already covers 100% of the semantics ('Keys to keep (comma-separated)'). The description adds no further meaning about the projection syntax or valid keys, so the baseline 3 for high schema coverage is appropriate.
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?
Specific verb (Get) plus resource (live race feed) with an explicit enumeration of what the feed contains: current lap, flag state, laps to go, leader, and per-vehicle running order. That enumeration clearly separates it from siblings like nascar_get_schedule and nascar_get_lap_times without needing to name them.
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 gives real usage context: when no race is live the response degrades to an idle state (flag_state 9, race_id -1), which tells the agent the tool is safe to call at any time and how to detect the no-race case. It does not name alternatives or explicit when-not-to-use conditions, so it stops short of a 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.