describe_streamOne stream in full: every column, the primary key, the source and its health.
Also what changed in the collector recently — a change in the collector is
a change in the data, and a step in a series may be one.
Args:
slug: The stream, e.g. ercot-realtime-lmp (list_streams names them).
| Name | Required | Description | Default |
|---|---|---|---|
| slug | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish read-only, idempotent, non-destructive behavior. The description adds value beyond this by disclosing that the output covers columns, primary key, source, health, and recent collector changes, including the subtle warning that a collector change can affect the data series.
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?
The description is front-loaded with the core purpose and stays compact. The second paragraph about collector changes is useful but somewhat cryptic ('a step in a series may be one'), preventing a perfect score for clarity of structure.
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 one-parameter read-only tool with a provided output schema, the description covers what the tool returns, how to obtain the slug, and the relevant behavioral nuance about collector changes. Nothing essential is missing for correct invocation.
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%, but the description compensates with the 'Args' block: it explains slug identifies the stream, gives a concrete example ('ercot-realtime-lmp'), and tells the agent where to get valid slugs (list_streams). This is sufficient for a single simple parameter.
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 states a specific verb and resource: 'describe_stream' returns one stream 'in full' with every column, primary key, source, and health. It also points to a sibling ('list_streams names them'), distinguishing the tool from a plain list and from query/column tools.
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 description gives clear context: use this for complete metadata about one stream, and obtain valid slugs via list_streams. It does not explicitly state when not to use it or name all alternatives, 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.
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