primer

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

No annotations are provided, so the description carries the full burden. It discloses that the tool retrieves 'up-to-date contextual information' and specifies the types (time, location, network environment), which is useful behavioral context. However, it lacks details on data freshness, privacy implications, or response format, leaving gaps for a tool that handles sensitive session data. This is adequate but not comprehensive.

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, front-loaded with the core purpose followed by usage guidance. Every word earns its place: the first sentence defines what the tool does, and the second specifies when to use it. There is no fluff or repetition, making it highly efficient and well-structured.

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 low complexity (0 parameters, no output schema, no annotations), the description is reasonably complete. It covers purpose, usage, and the types of information retrieved. However, without annotations or output schema, it could benefit from more detail on response structure or data sources, slightly limiting completeness for a session-context tool.

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 has 0 parameters with 100% coverage, so no parameter documentation is needed. The description appropriately doesn't discuss parameters, focusing instead on the tool's purpose and usage. This meets the baseline of 4 for zero-parameter tools, as it adds value without redundancy.

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 the tool's purpose: 'Get up-to-date contextual information of the current session to provide localized, time-aware responses.' It specifies the verb ('get') and resource ('contextual information'), and distinguishes it from sibling tools by focusing on session metadata rather than search, extraction, or processing operations. However, it doesn't explicitly differentiate from all siblings (e.g., 'show_api_key' might also provide session info), keeping it at 4 rather than 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?

The description provides explicit guidance on when to use the tool: 'Use this when you need to know the current time, user's location, or network environment to give more relevant and personalized information.' It clearly defines the triggering context (needing time, location, or network data for personalization) without needing to specify exclusions, as the context is distinct from sibling tools' purposes.

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