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

Annotations already declare readOnly and idempotent, but the description adds crucial behavioral traits: the payload is served from storage and never recomputed, ownership semantics (not found vs forbidden), and required auth scope (tickets:read). These go beyond annotations and help the agent anticipate edge cases and security requirements.

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?

The description is two sentences, front-loaded with the core purpose and then concise behavioral details. Every clause adds value, with no redundancy or vague language. It is efficiently structured for quick comprehension.

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?

Given it's a simple read operation with a single parameter and an output schema exists, the description covers all necessary context: return fields, storage behavior, ownership handling, and authentication. It is fully complete for an agent to correctly invoke the tool without ambiguity.

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 100% and the single parameter snapshot_id is already well described in the schema ('The snapshot's id, from list_portfolio_snapshots'). The description does not add further parameter-level detail (e.g., format constraints, examples) beyond what the schema provides, so baseline 3 is appropriate.

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 explicitly states the tool fetches one portfolio snapshot by id and enumerates the exact fields returned (label, schema version, rollup payload, content hash, recorder, timestamp). This distinguishes it from siblings like list_portfolio_snapshots (listing) and diff_portfolio_snapshots (comparison) while clearly specifying the resource and action.

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?

The description implies when to use it (to fetch a specific snapshot's stored details) and clarifies that the payload is not recomputed, so for current live data one would use other tools. However, it does not explicitly name alternatives or state when not to use it, though the param description references list_portfolio_snapshots as the source for ids, providing some context.

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