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

Annotations already declare a safe read-only operation, and the description adds substantive context beyond them: case-insensitive matching, nested-tag matching, path-sorted results, a limit-per-page model with has_more/next_offset pagination, and the operational note that it reads Markdown files directly so Obsidian need not be running.

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 dense sentences, front-loaded with what is searched and by what criteria. The third sentence restates return fields (path, title, first matching line, tags) that an existing output schema already covers, which is mild redundancy, though it also carries the pagination contract.

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 a zero-required-parameter search tool with a 100%-covered schema and an output schema, the definition is nearly complete: matching semantics, pagination, sort order, and the no-Obsidian-required fact are all present. It never clarifies what happens when `vault` is omitted while multiple vaults exist, leaving one ambiguity in an otherwise well-covered definition.

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 schema carries the field definitions, and the description still adds value: `query` is scoped to titles and text and is case-insensitive, `tag` matches both inline and frontmatter tags including nested ones, and `offset` is explicitly tied to next_offset from the prior page. `vault` is only referenced via the description's mention of obsidian_list_vaults.

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 names a specific verb and resource (search an Obsidian vault's notes) and enumerates the two match modes (text in titles/body, tag) plus the combined mode. It stops short of distinguishing itself from nearby siblings such as search_notes, list_notes, or obsidian_read_note, so an agent must infer which search surface to pick.

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 only implied: you search when you need to locate notes, and the parenthetical 'Optional when `query` is given' shows the two modes can combine. There is no explicit guidance on when to prefer this over list_notes, obsidian_read_note, or the generic search_notes, and no stated exclusions.

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