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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered; the description adds a genuine contract beyond that: "Never raises: a field that cannot be read is reported with source unavailable." That partial-failure behavior is the key thing an agent needs, though it says nothing about freshness/caching of the snapshot or cost of the call.

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?

Front-loaded with the resource and its fields, then usage triggers, then exclusions, then the failure contract and return keys. Every clause carries routing or behavioral information; there is no restatement of the name or title.

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?

No output schema exists, and the description compensates by naming the return shape `{battery, storage, arch, memory}` plus the degraded-value convention. Combined with the annotations and an empty input schema, an agent has everything needed to call it correctly.

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?

Zero parameters, so there is nothing to disambiguate and the baseline is 4. The description correctly signals a no-argument call by framing the tool as a snapshot rather than implying any query/filter options.

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?

States a specific verb and resource ("read-only snapshot of the host hardware and OS") and enumerates exactly which fields it covers: battery, storage, CPU architecture, memory. It explicitly separates itself from `server_health`, `resolve_path`, and `path_adapter`, so an agent can pick it without opening any schema.

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?

Gives concrete when-to-use triggers tied to the agent's task ("free space before a download, battery before a long job, arch before picking a binary") and an explicit when-not clause naming all three siblings with their distinct scopes. Nothing about routing is left to inference.

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

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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), and the description adds substantial context beyond them: it says the tool takes no arguments and enumerates the reported data, including env class, HOME/PREFIX/TMPDIR, Android roots, noexec mounts, and notes. It also lists the return fields, which is valuable given there is no output schema.

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?

Front-loads the core action, then adds the no-argument note, sibling boundary, and return shape without filler. The density is high but every sentence serves selection or invocation.

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 lack of an output schema, the description helpfully lists the returned keys and explains what environment information is reported. It is complete for a zero-parameter read-only diagnostic tool, though it could mention whether the reported environment is cached or live.

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 tool has zero parameters, so the baseline is 4; the description confirms "Takes no arguments," aligning with the empty schema. There are no parameter semantics beyond that, and none are needed.

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?

States a specific verb and resource: "Report the runtime's path environment," and immediately explains the practical purpose: translating host paths correctly. It also explicitly distinguishes itself from `resolve_path`, so an agent can identify the tool without opening sibling schemas.

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?

Gives an explicit routing rule: use `path_adapter` when the environment itself is unknown, and use `resolve_path` to validate a single candidate path. This names the alternative and the condition that selects it.

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

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

The annotations already establish read-only, idempotent, non-destructive behavior, and the description adds substantial context beyond that: variable expansion rules, symlink following, mount detection, Android-equivalent path spellings, and the exact result fields returned. There is no contradiction with the annotations.

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 definition is front-loaded and every major sentence contributes useful information. It is somewhat dense and run-on in the first sentence, but the density is justified by the number of path-expansion rules being communicated.

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?

There is no output schema, so the description appropriately lists the return object fields. With only one parameter, explicit annotations, detailed expansion semantics, sibling differentiation, and return-shape disclosure, an agent has everything needed to call the tool correctly.

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 adds meaningful semantics beyond the schema: concrete equivalent input forms, relative-path handling against the working directory, and the specific meanings of `~`, `$HOME`, `$PREFIX`, and `$TMPDIR`. The schema already covers required/non-empty behavior, so this is not a full 5.

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 states a specific verb and resource: resolving and validating one filesystem path, including expansion, symlink following, mount reporting, and alternative spellings. It explicitly distinguishes itself from the sibling `path_adapter`, so an agent can select it without inspecting either schema.

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 explicit when-to-use guidance: useful when a path must be handed to a shell command or another tool, and not needed for paths already known-good on plain Linux. It also draws a clear sibling boundary: `path_adapter` reports the environment map, while `resolve_path` reports one concrete path.

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

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real context beyond that: the scope is this server process rather than the device, it tracks live child processes, and it includes an Android-specific risk assessment. It stops short of saying anything about cost, frequency, or what an unhealthy result looks like, but the scope and content disclosure is solid.

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?

Front-loaded with the scope ("Read-only self-diagnostics for this MCP server process"), then the returned signals, then the usage boundary against `device_status`. The field enumeration is dense but each item is a distinct diagnostic the caller may need, so nothing reads as padding.

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 no output schema and no parameters, the description carries the full burden of telling the agent what comes back, and it does: it names the four top-level return keys {server, children, memory, phantom_process} and the highlights of each. An agent has everything it needs to decide to call it and to interpret the response shape.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no configuration is needed by framing the call as pure self-diagnostics, and it supplies no misleading parameter hints.

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?

States a specific verb and resource ("read-only self-diagnostics for this MCP server process") and enumerates exactly what it reports: pid/ppid, uptime, counters, children, RSS, Phantom Process Killer risk. It explicitly distinguishes itself from the sibling `device_status`, so an agent can route correctly without opening either schema.

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?

Gives three concrete triggers (verify the server is alive, debug client-side disconnects, check for accumulating orphaned children on Android) and an explicit exclusion with a named alternative: "Not for the device itself: use `device_status` for battery, storage, arch and memory."

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