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

Annotations already establish readOnly=true, destructive=false and openWorld=true, so the safety profile is covered. The description adds meaningful context beyond them: the call returns personal data and includes verified flags and custom data, which matters for handling and downstream use. It does not discuss error behavior for a missing id, keeping 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?

A single compact sentence front-loads the resource and contents, and every clause (fields, PII warning, endpoint) carries information. The endpoint path is slightly redundant with the tool name but serves as a mapping aid.

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 read with no output schema, listing the returned fields plus the PII warning gives an agent enough to call it and interpret the result. Not mentioning not-found behavior or id source failures is a minor remaining gap.

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%, with the lone subscription_id documented including its numeric pattern and origin. The description adds nothing beyond that (the endpoint template merely mirrors the parameter), so the baseline 3 applies.

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?

Names a specific verb and resource ('One subscription') and enumerates the fields returned, which distinguishes it from trumpia_list_subscriptions and trumpia_search_subscriptions by scope. It never explicitly names those siblings as alternatives, so the differentiation is implicit rather than stated.

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?

Retrieval is implied by 'One subscription... /subscription/{subscription_id}', and the schema notes the id comes 'from a list or search', hinting at the workflow. But there is no explicit when-to-use statement, no exclusion, and no pointer to a named alternative tool.

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