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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is partly covered. The description adds material context the annotations do not: the context string is transmitted to external developers, and therefore must not contain PII, secrets, or credentials. It still does not say what comes back or how/when the request is fulfilled, which keeps it short of a 5.

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?

Three sentences, all load-bearing: trigger, exclusions, and privacy constraint. The gating condition is front-loaded with 'Only call this when...', so the agent sees the routing rule first.

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 meta tool with annotations and no output schema, the description covers when to use it, when not to, and what is safe to send. The only gap is what the call returns or how the request is fulfilled, which a description of this kind could reasonably mention.

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 100%, so the baseline is 3, but the description meaningfully constrains the single parameter beyond the schema by prohibiting private information in it. That is a real usage rule for 'context', not a restatement of the field description.

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 establishes this as a fallback meta-tool whose input is forwarded to the mobile-mcp developers, which lets an agent infer that it requests capabilities not currently exposed. However, it never states the action plainly (e.g. 'request additional tools'), leaving the verb to inference. It is clearly distinguishable from every sibling, which all operate on a device rather than requesting new capability.

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?

It gives an explicit trigger ('only call this when none of the other tools can do what you need on a mobile device') plus two explicit exclusions ('do not call it for tasks unrelated to mobile', 'or when another tool already covers the task'). This is exactly the when/when-not/alternative structure that a fallback tool needs.

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