Recall context

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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them: it discloses the matching strategy, that hop expansion traverses [[wikilinks]], that results are packed under a token budget with overflow dropped, and the full return shape. The note that systemPrompt marks notes as reference data rather than instructions is a meaningful trust-boundary disclosure an agent cannot infer from structured fields.

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?

Front-loaded with purpose and effect, then usage guidance, then return shape, then the disambiguation sentence. Nearly every clause carries information, though the mechanism clause and the return-value enumeration make it denser than strictly necessary.

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?

No output schema exists, and the description compensates by naming the returned fields and explaining the role of the key one (systemPrompt as a ready-to-use, reference-marked context block). For a three-parameter read tool with a non-obvious retrieval pipeline, nothing an agent needs to call it correctly is missing.

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%, so the baseline is 3, but the description adds pipeline-level meaning: it explains what hops actually do (follow wikilinks outward from matches) and what maxTokens controls (the packing budget, with omissions when exceeded). It stops short of restating defaults or caps, which the schema already handles.

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 ("Recall relevant memory for a query from the shared Second Brain vault") and then describes the retrieval pipeline: keyword/recency matching, optional semantic similarity, wikilink expansion, token packing. It explicitly names the sibling it is not (brain_search) and the condition that distinguishes them.

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 an explicit trigger ("Call this before answering anything that earlier work may already cover: past decisions, constraints, research, project background") plus a named alternative and the exact condition for choosing it ("Use brain_search instead when you only need a ranked list of matching notes"). Both when-to-use and when-to-use-something-else are covered.

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