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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial behavior beyond them: per-item error semantics, a retry instruction for unavailable feedback, handling rules for unknown vs partial support, a scoping caveat that subscription fields refer to the primary device and not linked devices, and an untrusted-data warning plus citation requirement.

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 core action and scope, then moves to aggregation contents, then caveats. Every sentence is functional, though the run of eight short clauses (errors, unknown support, subscription fields, untrusted data, citing URLs) reads as an undifferentiated list rather than grouped guidance.

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 read-only aggregation tool with an output schema already defining return shape, the description covers everything an agent needs: scope limit, what is aggregated, error handling, caveats about support status and subscription scoping, and a prompt-injection warning. Nothing material to correct invocation is missing.

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 50%: modIds and modelId are documented in-schema, while deviceId and platform carry no description. The description adds the intent behind the optional device/model/platform parameters ('optional device/model/platform fit'), which gives them meaning the bare schema lacks, but it supplies no format or constraint detail to compensate for the undocumented half.

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 (compare mods) with a hard scope (up to four shortlisted mods in one call) and explicitly names what it aggregates: the same details as get_mod plus three newest get_feedback entries. An agent can distinguish it from get_mod and get_feedback 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?

Explicitly routes the agent away from the sibling reads: 'This replaces those separate reads when feedbackStatus is available,' and instructs 'retry unavailable feedback before recommending.' There is no explicit statement of when to prefer the individual get_mod/get_feedback calls instead, so it stops just short of full when/when-not coverage.

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