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

Annotations already cover read-only/idempotent safety, and the description adds real context beyond them: how the digest is consumed (appended by every generation path), and what has_material:false signals about fallback behavior. It stops short of describing payload size or shape, but that is a minor gap given no output schema exists.

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?

Three sentences, front-loaded with the return content, followed by the flag semantics and the usage trigger. Dense but no filler; the parenthetical list is efficient rather than verbose.

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 does the work of explaining the return: digest contents plus the has_material flag. That is enough for an agent to call it correctly; only the absence of a pointer to build_material for the has_material:false case leaves a small gap.

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?

There is one required parameter, account_id, fully documented in the schema (100% coverage). The description adds nothing about scoping or format for account_id, so the schema carries all semantic weight — baseline 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?

States a specific verb and resource ('Returns the account's material digest') and enumerates the digest contents (identity, claims, experiences, FAQ, sourced numbers, voice). It does not explicitly differentiate from the sibling build_material, so an agent must infer the read-vs-build distinction from the verb alone.

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 a clear trigger: call it 'before generating when it is unclear whether the account has material.' It does not name the obvious alternative (build_material) or state when the digest is unnecessary, so routing is good but not exhaustive.

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