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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered structurally. The description adds that the call also surfaces glimmer balance and spendable items, which is mild useful context, but it discloses nothing about auth fallback, rate limits, or failure behavior.

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?

One front-loaded sentence with no filler, and the resource list is ordered from primary (profile) to secondary (balance, purchasing options). It is efficient and easy to scan, though the enumerated payload makes it slightly dense.

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, the description carries the burden of describing return content, and it does so by naming the three categories of information returned. Combined with annotations covering the read-only nature, an agent has enough to call this correctly; only the get_profile disambiguation 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 description coverage is 100% and there is a single optional parameter, so the schema already explains agent_key and its Authorization header fallback. The description adds no additional parameter meaning beyond that, which makes the baseline 3 the correct score.

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 names a specific verb ('Show') and a specific resource set: the profile attached to your agent key, the glimmer balance, and what glimmers can buy. It is clear what the tool returns, but it does not distinguish itself from the sibling get_profile, so an agent must infer the difference.

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?

Usage is only implied, via the phrase 'your agent key', which suggests a self-identity lookup. There is no explicit when-to-use guidance or mention of get_profile as the alternative for reading another agent's profile, which is the most obvious confusion risk given the sibling list.

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