context

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

readOnlyHint already tells the agent this is a safe read, so the bar is lower; the description still adds real behavior — depth=1 pulls in neighbours (a cost/scope signal), detail levels run up to 'full (audit)', and as_known_at yields a historical view. However, nothing is said about result size, truncation, or how only/exclude narrow output, which is exactly the kind of behavioral detail this tool needs.

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 core question is front-loaded in the first clause, and the remainder is a compact parameter gloss with no filler. It is so compressed that a few fragments ('task: its memory') become hard to parse, which slightly undercuts the terseness.

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 an 8-parameter tool with no output schema, the description covers the query and most filtering semantics but omits any statement of return shape and says nothing about two of the parameters. An agent could call it, but would be guessing about output size and the meaning of `only`/`exclude`.

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 0%, so the description must carry the load, and it does for most of it: subject format ('<kind>:<id>' or a list), as_of, as_known_at, depth semantics, and the detail enum with its default. It leaves `only`, `exclude`, and `task` opaque ('its memory' is cryptic), so it compensates well but not completely for the 8 undescribed parameters.

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 states a specific question the tool answers — 'What is true about a subject now or at as_of' — and enumerates the payload (facts with `since`, relations, rule evaluations), which pins down the resource better than the bare name 'context' does. It implies a current-state/temporal-query role that distinguishes it from a logged `history`, though it never explicitly names its siblings.

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?

It gestures at when the tool applies ('now or at as_of', 'as Keel knew it then'), but there is no explicit guidance on choosing it over `history`, `search`, `related`, or `annotate`. The rest of the text is parameter gloss rather than usage policy, and no when-not conditions are given.

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