source_snapshot

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

Annotations already declare read-only, idempotent and non-destructive, so the safety profile is covered. The description adds real context beyond that: the returned data is the immutable original plus acquisition proof, and a capture does not confer truth, independence or learning eligibility — a meaningful interpretation guardrail an agent would not get from the annotations. It does not say what happens when the snapshot_id is unknown.

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 short sentences (plus the caveat line) with the core action front-loaded and no filler. The caveat is somewhat detached from the main sentence and reads as an appended note rather than integrated guidance, which is the only structural weakness.

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 single-parameter read tool with an output schema and full annotation coverage, the definition supplies what an agent needs to call it and to interpret the result carefully. Missing only edge-case behavior such as invalid or stale snapshot_id, which is a minor gap given the low complexity.

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 snapshot_id property already explains it must be an exact source_snapshot_id from pending_news or event provenance. The description only reinforces the 'one source version' framing, adding no resolution rules or format detail beyond the schema, so the baseline of 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 first sentence gives a specific verb and resource ('Read the immutable original input and acquisition proof for one source version'), which is far more precise than the tool name alone. The second sentence disambiguates the scope of the identifier ('a backend_snapshot locator identifies a captured API item, not an upstream webpage'), though no sibling tool is named for contrast.

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 is implied rather than stated: you fetch this when you need the immutable original plus acquisition proof for a known version. The closing caveat ('source capture alone does not prove truth, independence or learning eligibility') usefully bounds what the result may be used for, but there is no explicit when-not-to-use rule or named alternative among siblings such as pending_news or event_history.

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