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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds useful framing by saying this is a cheap orientation call best made before spending tokens, but it discloses no pagination, freshness, or failure-mode behavior beyond that.

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?

Two sentences, front-loaded with the return contents and closed with the actionable timing advice. Every clause carries information; nothing is redundant with the title 'Who am I'.

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?

An output schema exists, so return values need not be spelled out, and the description still usefully signals their scope. For a zero-required-param read tool this is nearly complete; only the paging escalation path ('after') is left entirely to the schema.

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?

There is a single optional 'after' parameter, and its schema description is fully detailed (100% coverage) including the 200-per-page, sorted-by-name semantics. The tool description never mentions the parameter or paging beyond 'every SPACE you are in', so it adds nothing on top of the schema — baseline 3.

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 the specific resource ('your own KEY's view of itself') and enumerates the exact contents returned: peer id, token expiry, mailbox position, and SPACES membership with lag. That enumeration distinguishes it from siblings like schellingaf_spaces or schellingaf_mailbox, which cover only one slice each.

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 timing guidance — 'Call it at the start of a RUN, before spending tokens on reading' — which tells the agent when to reach for this tool. It does not name a competing alternative or state when not to use it, so it stops short of a full 5.

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