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

Beyond the readOnly/idempotent annotations, it discloses plan-gated behavior (locked fields return null and are named in the `locked` list, `lockedCount` shows how many more results a higher plan reveals), instructs the agent to say data is on a higher plan and never estimate it, and clarifies that results are not yet shown to the user. This is unusually rich behavioral context.

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-loaded with purpose and organized into output sections, semantics, plan behavior, and handoff. Nearly every sentence carries weight, though the density is high and it takes effort to parse compared to a truly lean definition.

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 and a fairly complex tool, the description compensates by describing the result sections, entitlement/locked behavior, the resultId handoff to sightglass_show, and the account requirement. An agent has everything needed to call and route it correctly.

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 67% and the description adds real meaning: groupBy defaults to company, categoryId drives the categories-to-leaders drill-down and comes from this tool's own `categories` result. The `limit` and `weeks` params are left to the schema, so it stops short of full coverage.

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 (the market view: who holds what share of active ads, week by week) and enumerates the returned sections (pulse, share, categories, leaders). It clearly distinguishes itself from siblings like sightglass_show (display) and sightglass_find_ads (ad-level search).

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?

Explicitly names the follow-up: call sightglass_show once with the resultId to render cards, and notes show does not search again. Also states it works without a Replo account and should be called before asking the user to sign in, giving clear ordering guidance.

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