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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds real behavior beyond that by noting the accounts returned are only *confirmed* library accounts and that reads are scoped to the active Space session binding. The override semantics are conveyed, though the description does not cover failure behavior for an unknown competitor_id.

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 compact sentences, front-loaded with what is returned and followed by the scoping caveat. The scoping sentence largely restates the space_id schema description, which is mild redundancy but not enough to warrant trimming.

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 simple two-parameter read tool with no output schema, the description tells the agent what the result contains (competitor, confirmed ad library accounts, summary) and how the Space context is resolved. Nothing essential to calling it correctly 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 the space_id field already spells out the override-versus-session default in more detail than the description does. The description adds no meaning to competitor_id beyond what the schema states, so 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?

The description states the resource precisely — a single competitor returned with its confirmed ad library accounts and a summary — which lets an agent distinguish it from list_competitors (plural) in the sibling set. The verb is implicit ('one competitor with...') rather than an explicit 'get', but the singular scope is unambiguous.

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 guidance is limited to Space scoping: read the active Space, use set_active_space to switch, or pass space_id as a one-call override. There is no guidance on when to choose this over list_competitors, get_competitor_coverage, or get_competitor_auction, so the retrieval-singular use case is only implied by the description.

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