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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description goes well beyond that, disclosing plan-gating behavior (missing fields return null and are named in `locked`, `lockedCount` signals hidden results) and the two-step fetch-then-show interaction model. These are exactly the traits an agent could not infer from the structured fields.

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 what is fetched, then plan-gating semantics, then the show hand-off. Dense but each clause carries information; the 'Returns data only: nothing is shown to the user yet' pair is slightly redundant but reinforces a non-obvious point.

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 fully carries the burden of describing the return payload, plan-locked nulls, lockedCount meaning, and the required follow-up call. An agent has everything needed to call it and to handle the response 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 description coverage is 67%: projectId and workspaceId are documented in the schema (including the multi-workspace requirement), but sitePageId has no schema description and the prose adds no syntax or sourcing detail for it. Baseline 3 is appropriate since the schema carries most of the parameter meaning.

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 gives a specific verb (Fetch) and enumerates exactly what comes back: screenshots as viewable URLs, detected technology stack, traffic estimates, and live-ad counts. This clearly separates it from sightglass_find_site_pages (search) and sightglass_get_site_page_versions (versions). It stops short of naming those siblings explicitly, so it lands at 4 rather than 5.

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?

Strong workflow guidance: it states that results are data-only, that the answer must be surfaced via a single sightglass_show call using this call's resultId, and warns against self-estimating plan-locked data. It does not state when to prefer this over get_site_page_versions or find_site_pages, so no explicit alternatives are given.

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