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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains data retention (30 days), the impact of recently added APIs (few/null data points), and clarifies that null percentages are expected rather than 100%. This adds valuable context beyond the schema, though it stops short of describing return structure or potential errors.

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 two sentences long, front-loaded with the core output (uptime percentages, response-time stats, data points) and followed by a valuable caveat about retention. No words are wasted, and every sentence contributes to understanding the tool's behavior.

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?

Given the tool's simplicity (2 parameters, no output schema), the description provides sufficient context for basic use. It covers what the tool returns and a key edge case (null percentages for recent APIs). However, it leaves some ambiguity about the exact format of response-time stats and does not explicitly state the default range, which the schema handles. Overall, it is complete for typical usage.

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 input schema already provides 100% coverage of both parameters (slug and range), so the description adds minimal semantic value. It mentions 'one API' and 'time range', which map to the parameters, but does not elaborate on allowed values or defaults beyond what the schema's enum and descriptions already state. Baseline 3 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?

The description clearly states that the tool returns uptime percentages, response-time stats, and recorded data points for one API over a time range. This specific verb-resource pairing distinguishes it from siblings like get_api_status (which likely returns current status) and list_apis (which lists APIs), making its purpose 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 description implies the tool is for historical uptime data but does not explicitly mention when to use it over alternatives like get_api_status or list_down_apis. It provides no exclusions or alternative recommendations, though the context of 'history' and 'one API' gives a reasonable hint. This is adequate but lacks explicit guidance.

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