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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds substantial context beyond them: plan-gated fields return null and are enumerated in `locked`, `lockedCount` explains truncated results, and it instructs the agent to tell the user the data is on a higher plan rather than estimating. It also discloses that the call returns data only and requires a follow-up sightglass_show with the resultId.

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-loads what the tool is and its sibling relationship, then layers filtering, plan-gating, and the show workflow in a single dense paragraph. Every sentence carries information, though the run-on structure of the middle sentences makes it slightly harder to scan than it needs to be.

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 correctly explains the return shape's notable behaviors (null + `locked` for plan-gated fields, `lockedCount`) and the resultId handoff to sightglass_show. It is a tool with 8 params and no required ones, and the gaps are the unmentioned `days`/`limit` semantics and pagination limits.

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 75% and four parameters are enums, so the schema already carries most semantics. The description adds meaning for `type`, `ageBand`, `awareness` and the sort options, but says nothing about `days`, `limit`, defaults, or why `projectId`/`workspaceId` both exist. This is baseline-level support on top of an already-documented schema, not compensation.

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 (angles) and pins the scope as cross-brand: 'the angles in use across every tracked brand.' It explicitly positions itself against the sibling sightglass_find_angles ('the same shape as sightglass_find_angles, with the brand on each'), so an agent can distinguish the two without opening either 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?

Gives concrete usage contexts ('what pitches are brands using on this audience', 'find an angle nobody is running') and names the filters and sorts available. It implies but never explicitly states when to reach for sightglass_find_angles instead of this cross-brand variant, so the routing guidance stops short of a full when-not statement.

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