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

No annotations are present, so the description carries the full burden. It only says 'Expression discarded' but there is no expression parameter, leaving all behavior opaque. There is no disclosure of side effects, data handling, or what is actually evaluated or checked.

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 vague sentence, which is not effective conciseness but under-specification. It omits critical details about what the tool does and how parameters relate.

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 9 parameters, no output schema, and no annotations, this description is grossly insufficient. It doesn't explain what the tool does with any parameter or what the agent can expect from the call.

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 descriptions cover 100% of parameters, so the baseline is 3, but the tool description actively misleads by referencing arithmetic while the parameters are about URLs, timezones, and search text. The description adds no clarifying value and may cause the agent to misuse the parameters.

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 claims 'Evaluate a+b style arithmetic' but the input schema has no arithmetic expression parameter—instead it lists git refs, URLs, cities, JSON, etc. This is misleading and fails to convey what the tool actually does. It doesn't distinguish from siblings like browser-url-ok or validate-json.

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 any of the 27 siblings. There is no mention of conditions, exclusions, or alternatives. The agent gets no help deciding between calc-eval and other URL/JSON/city-oriented tools.

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