pii_sessions

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

Annotations already declare the safe read profile (readOnly=true, destructive=false), so the bar is lower, yet the description still adds real value: it scopes the payload ('no ciphertext, no plaintext') and discloses the failure mode (ok:false when no encryption key is configured) with concrete remediation (DATASENTRY_ENCRYPTION_KEY or rotate-key).

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 sentences, no filler: the scope and returned fields come first, the error/edge case second. Every clause earns its place and the most important information is front-loaded.

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 carries the burden of describing returns and does so partially (key version, creation time, absence of ciphertext/plaintext) plus the error path. It omits ordering, volume or pagination behavior for a session listing, which is a minor remaining gap for a zero-parameter tool.

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?

Zero parameters, so per the rubric the baseline is 4; the schema is empty and the description correctly refrains from inventing filter semantics, instead describing what the unfiltered result contains.

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?

Specific verb+resource ('List PII encryption sessions') with the returned fields named ('key version and creation time'). It distinguishes itself from mutating siblings like pii_delete_session, pii_purge_sessions and pii_rotate_key by resource+action, though it never names an alternative explicitly.

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: an agent can infer this is the read path for inspecting encryption sessions, but there is no 'use this when / not when' guidance or routing to pii_rotate_key versus pii_purge_sessions. The remediation hint for the missing-key error is useful prerequisite context but not a usage rule.

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