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

No annotations provided. The description mentions adding a parameter but doesn't disclose whether it overwrites existing keys, validates the URL, or handles special characters. The behavioral implications are largely unspecified, leaving the agent uncertain about side effects.

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 a single concise sentence with no unnecessary words. While it could benefit from more structure (e.g., stating if it handles duplicate keys), it is appropriately sized for a simple tool.

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 existence of many URL-related sibling tools, the description lacks context on how this tool fits in. It doesn't mention edge cases (e.g., existing query string, invalid URL) or that it returns a modified URL, though an output schema likely covers that. Completeness is insufficient for an agent to use it correctly in varied scenarios.

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 description coverage is 100%, so the schema already defines each parameter. The description adds no additional semantic meaning beyond what the schema provides, warranting a baseline score of 3.

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 'Add a query parameter to a URL' clearly states the action (add) and the resource (query parameter to a URL). It effectively distinguishes from sibling tools like 'remove_query_param' (removes) and 'build_url' (constructs from components).

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?

No guidance on when to use this tool versus alternatives. For example, it doesn't mention when to prefer 'build_url' or 'parse_url' over this tool, nor does it specify any prerequisites or exclusions.

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